Note: Descriptions are shown in the official language in which they were submitted.
CA 02492712 2005-01-07 'y. Docket No. 01-451 PCT
TITLE OF THE INVENTION
[0001] Apparatus for Applying Ink Indicia to Boards
BACKGROUND OF THE INVENTION
[0002] Wood boards or sheets, typically made from wood composite products like
plywood or oriented strand board, are common construction materials in
commercial, industrial
and residential buildings. During construction, these boards are placed over
and fastened to an
underlying supporting frame to form the wall, roof or floor of the building.
In order to improve
the efficiency of fastening the boards to this frame, a pattern may be printed
on the board or
panel in order to rapidly attach the board to the frame structure.
[0003] Typically, ink is applied onto a board to form these patterns during
the last stage
of manufacture, shortly before the boards are packaged and readied for
shipment. Most
manufacturers perform this marking step at approximately the same speed as the
speed at which
the boards are inspected for defects so as to not interfere or impede board
production.
Unfortunately this high marking speed reduces the accuracy and intricacy of
patterns that can
be formed during marking, which may result in marking patterns that are simple
or crude.
While such markings might provide a minimally useful set of reference points,
they do not
maximize product versatility nor impart any special distinctiveness to the
product.
[0004] One way to improve the marking process is to reduce the separation
between the
surface of the board and printheads of the printing system (commonly referred
to as the "throw
distance") that apply ink to the board (typically the printing system includes
several print
heads). When the throw distance is small, more accurate and intricate patterns
may be formed
on the board. However, such small separations between the surface of the board
and the print
heads also increases the possibility that during manufacture a board that is
oversized, warped,
misaligned or has a non-uniform thickness may accidentally contact the print
heads and
severely damage or destroy them. Because of this, a consistent gap must be
maintained
between the boards and the print heads. Furthermore, these variations of the
board thickness
and height can compromise the accuracy with which the ink is applied to
desired locations on
the boards thus, further deteriorating the quality of the patterns formed on
the board surface.
[0005] Accordingly, there is a need for an apparatus to apply ink to the
printing surface,
wherein small separations between the boards and the ink application system
can be used to
enable intricate and accurate printing of complex patterns and designs at high
production
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speeds. Furthermore, it is also desirable that the apparatus should have means
for applying a
normal force at several locations on the print surface to the boards to keep
the printing surface
of the boards in a flat, planar shape, the planar shape increases the accuracy
of the locations that
the inks are applied to the printing surface and thereby increases the quality
of the patterns,
marks, and ornamental designs formed on the printing surface of the boards.
BRIEF SUMMARY OF THE INVENTION
[0006] What has been invented is an apparatus for applying ink patterns on
boards,
including: means for serially moving the boards in a selected direction and
through a
predetermined space; means for applying ink, said means for applying ink being
movable from
a first position adjacent the predetermined space to a second position remote
from the
predetermined space; and means for detecting boards moving in the selected
direction and
having a part thereof outside the predetermined space. The apparatus also
includes: means
responsive to the detecting means, for moving the means for applying ink from
the first position
to the second position when a board traveling in the selected direction is
outside the
predetermined space, whereby contact between moving boards and said means for
applying ink
is avoided; and means for controlling the means for applying ink to apply the
ink patterns on
the boards traveling within the predetermined space.
[0007] A feature of the invention is that the apparatus is capable of applying
ink
patterns on boards moving at rates of about 150 ft/min to 600 ftJmin.
[0008] Another feature of the invention resides in that ink can be applied to
boards at desired
locations, as they move, with an accuracy of V 0.125 inches.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0009] The foregoing summary, as well as the following detailed description of
preferred embodiments of the invention, will be better understood when read in
conjunction
with the appended drawings. For the purpose of illustrating the invention,
there is shown in the
drawings embodiments which are presently preferred. It should be understood,
however, that
the invention is not limited to the precise arrangements and instrumentalities
shown. In the
drawings:
[0010] Fig. 1 is a perspective view showing the arrangement of an apparatus
for
applying ink to boards, according to a preferred embodiment of the present
invention;
[0011] Fig. 2 is a partial elevated side view of the apparatus, showing a
movable
carriage, prepared according to the present invention; and
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[00121 Fig. 3 is a rear perspective view of a modified apparatus, according to
the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0013]
[0014] As used herein, "board" is intended to include boards or sheets,
typically made
from wood composite products like plywood or oriented strand board, as well as
composite
panels that are made from a blend of wood, polymer and mineral materials.
Mineral or
polymeric fiber are also suitable for use.
[0015] By "wood composite material" it is meant a composite material that
comprises
wood and one or more other additives, such as adhesives or waxes. The wood is
typically in
the form of veneers, flakes, strands, wafers, particles, and chips. Non-
limiting examples of
wood composite materials include oriented strand board ("OSB"), waferboard,
particle board,
chipboard, medium-density fiberboard, plywood, and boards that are a composite
of strands and
ply veneers. As used herein, "flakes", "strands", "chips", "particles", and
"wafers" are
considered equivalent to one another and are used interchangeably. A non-
exclusive
description of wood composite materials may be found in the Supplement Volume
to the Kirk-
Rothmer Encyclopedia of Chemical Technology, pp 765-810, 6th Edition.
[0016] The present invention is directed to an apparatus for applying ink to
boards to
form simple marks and patterns as well as more complicated ornamental designs.
Typically
these boards are made from a wood composite material, especially oriented
strand board
("OSB"). Physically, these boards are typically 4 ft by 8 ft and 0.25 inches
to 1.5 inches thick,
and thus, weigh in the range of 20 lbs to 2001bs. In this apparatus, boards
are moved through a
predeterrnined space, and a means for applying ink onto a print surface of the
boards is, in its
first position, located adjacent the predetermined space. The apparatus also
contains a means
for detecting boards having a part outside the predetermined space (because,
e.g., the board is
warped or has a non-uniform thickness), as well as means responsive to the
detecting means for
moving the means for applying ink from the first position to the a second
positions when a
board traveling in the selected direction is outside the predetermined space,
thereby avoiding
contact between moving boards and the applying means and thereby preventing
damage to the
applying means and the electronics contained therein. As a second form of
protection for the
applying means, it is preferable to include a plurality of pinch rollers for
biasing boards moving
through the predetermined space against a plurality of drive rollers. The
drive rollers are
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disposed to contact the boards at points in a common plane and rotate about
parallel axis to
serially move the boards.
[0017] Through the combined use of these protective mechanisms, as well as
other
means discussed below, the separation between the boards and the means for
applying ink (the
throw distance) can be greatly reduced thereby improving the quality of the
marks and designs
formed by the ink on the board without incurring a significant risk of
damaging the applying
means. Moreover, because of this small separation between the applying means
and the boards,
the boards can be marked at much higher speeds.
[0018] Furthermore the pinch rollers bias the boards against a plurality of
drive rollers,
desirably keeping the printing surface of the boards in a flat, planar shape
as the boards pass
through the predetermined space and under the applying means. By maintaining
the printing
surface in this shape, the accuracy and intricacy of the patterns and designs
printed by the
applying means on the board can be improved.
[0019] Referring now to figure 1, a preferred embodiment of an apparatus 1 for
printing
marks on boards is shown. The apparatus includes a frame 11 (partially shown)
for supporting
the boards 4 as the boards 4 move serially through the apparatus 1. A
preferable frame 11 is a
Globe~m 16Q hold-down device made by the Globe Machine Manufacturing, Tacoma,
Washington. This frame 11 conveys the boards 4 from the fin.al stages of the
OSB
manufacturing line (not shown) in the selected direction 23 to the
predetermined space 17
where ink is applied onto the print surface 20 of the boards 4 (the print
surface 20 is that area
of the boards on which the ink is injected or applied to print marks or
designs). The
predetermined space 17 is a rectangular space having a length and width
commensurate with
the length and width of the means for applying in to the boards, and the
predetermined space 17
has a thickness about equal to the thickness of boards to be process plus the
desired throw
distance.
[0020] The apparatus 1 further includes means for serially moving the boards
in the
selected direction 23. The means for moving the boards in a forward direction
are a motor 50
responsive to a controller 44 and mechanical apparatus (not shown) connecting
the motor to the
plurality of drive rollers 26. These drive rollers 26 are located on four
shafts 62 below the
board level, and preferably each of these drive rollers 26 is made from steel
and coated with
rubber or some other material that reduces slippage and establishes a good
grip on the boards 4
to move them forward.
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[0021] The means for serially moving the boards also preferably comprises a
series of
pinch rollers for biasing the boards moving in the selected direction 23 and
through the
predetermined space 17 against the drive rollers. As shown in the figures, the
pinch rollers 29
are on shafts located above the level of the boards 4, and vertically above
each of the drive
rollers 26 is a corresponding pinch roller 29. In operation, each of the pinch
rollers 29 engage
the boards 4 and supply a biasing force substantially normal to the print
surface of the board 4
to keep the print surface flat and planar so as to improve the accuracy with
which ink is applied
to the print surface. Preferably a uniform bias force distribution is applied
to the panel that
does not interfere with the desired print pattern. The pinch rollers 29 are
set to a predetermined
gap from the drive rollers 26, and a predetermined compression is set using a
spring or
pneumatic actuator to maintain the biasing force on the board surface. This
configuration
maximizes the planar configuration to ensure a uniform print gap, while
minimizing slippage of
the boards as they pass over the drive rollers 26 to enhance speed control. It
is worth noting
that the means for supporting the pinch rollers is not illustrated in Figure 1
in order to allow the
exact positioning and spacing of the pinch rollers under the boards to be
shown. A person of
ordinary skill in the art would be capable of preparing a structure that would
support the pinch
rollers while allowing them to freely rotate, the rotation being powered by
the motor drive 50.
The structure supporting the pinch rollers may or may not be part of the frame
11 element.
[0022] With the drive rollers 26 moving the boards 4 in the selected direction
23, and
the pinch rollers 29 providing a normal forces to the printing surface 20 to
keep it flat, the
boards 4 move serially through the apparatus 1 and through the predetermined
space 17. When
the applying means are in the first position, the applying means are adjacent
the predetermined
space 17 as shown in Figure 1(in the figure the applying means are represented
by mounting
plate 35 ink jet printheads, discussed in greater detail below), and as boards
4 enter into the
predetermined space 17, marks are placed upon the boards 4 by the applying
means. The
applying means can be moved from the first position to a second position,
which is remote from
the predetermined space, in order to avoid damage to the applying means in
case a part of a
board moving in the select direction falls outside of the predetermined space
(perhaps because
the board is warped or of a non-uniform thickness).
[0023] In order to make use of the mobility of the applying means, the present
apparatus also includes means for detecting when part of a board falls outside
of the
predetermined space, as well as means responsive to the detecting means for
moving the
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applying means from the first position to the second position. The detecting
means monitors
the boards 4 moving in the selected direction, and if a part of the board is
outside the
predetermined space (and is thus too close to the means for applying ink) then
the means
responsive to the detecting means moves the applying means form the first
position to the
second position, and thus out of harm's way. Suitable detection equipment such
as trip
switches, lasers, sonar systems, or any other form of analytical detection
equipment. If these
electronic devices detect that a part of the board is outside the
predetermined space 17, they
generate a signal, which is then transmitted to the responsive means to
initiate the movement of
the applying means from the first position to the second position to prevent
damage to the
applying means. Also suitable is a preferred device that functions not by
electronic, sonic or
light sensing, but by mechanical action, such as a spring, discussed in
greater detail herein
below.
[0024] The applying means includes a carriage 32 pivotally coupled to the
frame 11.
The carriage has a mounting plate 35, and a number of ink jet printheads are
coupled to the
mounting plate 35. Preferably the ink jet printheads 38 are positioned so as
to be oriented in a
uniform print direction for easy message creation and maximized printing
accuracy. Mounting
in modular plates allows easy exchange among new and spare parts and reduces
manufacturing
cost. Each ink jet printer is best mounted recessed from the bottom of the
mounting plate 35
for protection from chips, flakes, or splinters. However, they may be mounted
flush with the
bottom of the mounting plate 35 in order to reduce the throw distance. To
improve the
resolution of the marks and ornamental designs imprinted on the board, it is
preferred that the
applying means, such as the ink jets, should be positioned about 0.0625 to
about 0.125 inches
above the print surface on the board 4.
[0025] In some situations, a part of the board will be positioned slightly
outside the
predetermined space, in which case rather than causing the movement of the
applying means,
the part of the board outside the predetermined space may instead be guided by
a deflector 101
into the predetermined space 17, with minimal interruption of the marking
operation. The
deflector 101 is best seen in Figure 2. It has a deflector 101 This deflecting
means is illustrated
in figure 2 as a beveled guide edge 101 located on the carriage 32. This
provides yet another
way of preventing the boards from damaging the applying means, and this
protective
mechanism has the further advantage of not interrupting the printing
operation. Indeed, in this
aspect of the invention, the sheer mass of the mounting plate provides a
significant amount of
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CA 02492712 2005-01-07
impact absorption to provide further protection to the ink applying means,
such as the inkjet
printheads.
[0026] Figures 1 and 2 also show means for detecting when a part of the board
lies
outside the predetermined space, as well as means responsive to the detecting
means for
moving the means for applying ink from the first position to the second
position when a board
traveling in the selected direction is outside the predetermined space.
Specifically, the carriage
32 is pivotably attached to the vertical support 104 at a bracket 110, the
bracket 110 being
located adjacent to the free end of the vertical support 104. One end 119 of a
coil spring 113 is
attached to the vertical support 104 below the bracket 110, while the opposite
end 116 of the
coil spring 113 is attached adjacent to the carriage near the unattached end
of the mounting
plate. When the apparatus is operating in normal printing mode, i.e., the
carriage is in the first
position as shown in solid lines) and is applying ink onto the boards 4, the
mounting plate 35 is
positioned over the predetermined space 17, and is substantially parallel to
the print surface of
the board 4. When the carriage 32 is in this first position, the spring 113 is
under compression
and stores potential energy. Additionally, an abutting piece 107 may be
present to limit the
counterclockwise movement of the mounting plate 35 through a fixed range.
[0027] Operatively, as the board moves in the selected direction 23, and if a
part of the
board is outside the predetermined space so that the board contacts the
carriage 32 with a
threshold force (more fully described below) then a portion of the kinetic
energy of the board is
transferred to the spring 113. The spring 113 then extends and, converting the
stored potential
energy into kinetic energy, causes the carriage 32 to pivot clockwise away
from the
predetermined space 17 into the second position so that the boards 4 to pass
harmlessly through
the predetermined space 17 without damaging the ink jet printheads 38 (in Fig.
2, the second
position of the mounting plate 35 is shown in broken lines).
[0028] Thus, the detecting means includes the deflector 101 and the mechanical
action
of the spring itself. If the force with which a board contacts the carriage 32
is sufficient then it
and the force exerted by the coil spring 113 in compression, then the spring
113 is taken out of
compression and swings the carriage 32 clockwise around the pivot point 110,
until it reaches
the second position, which is an equilibrium point where the spring is
extended and in tension
and the force of the spring pushing outward balances the force of gravity
pulling the carriage
32. Thus, the strength of the spring 113 (the value of the spring constant)
itself determines the
amount of force necessary to initiate the movement of the mounting plate 35,
and thus, the
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spring functions as the detecting means for determining when a part of the
board is sufficiently
outside the predetermined space 17 as to require rotation of the carriage 32.
It is worth noting
that the spring 113 is also a part of the means responsive to the detecting
means for moving the
applying means (the applying means including the carriage 32) from the first
position to the
second position. Besides a spring, gas shocks may also be used to determine
the force need to
rotate the carriage. By using gas shocks, the amount of pre-loading applied to
the gas shock
can be precisely controlled, so that the sensitivity of the carriage to
potential impacts can be
precisely specified. Additionally, the apparatus also preferably includes a
handle 99 so that the
position of the carriage can be manually adjusted.
[0029] The apparatus includes vertical adjusting means to adjust the distance
between
the applying means and the print surface of the boards (the throw distance).
This distance can
be made smaller so as to optimize print quality, or larger in order to
accommodate thick boards
or boards having a significant amount of variation in thickness. Although not
shown in the
embodiments, the vertical adjustment is provided by linear actuators driven on
a common shaft
to assure parallel height adjustments. Which allows easy incorporation of a
height gauge.
Preferably the linear actuators are driven either electrically or
pneumatically.
[0030] As discussed above, the applying means preferably makes use of ink jet
technology. Preferably, the ink jets are present as multiple ink heads
consisting of a
multiplicity of valves, each valve equipped to apply ink onto the print
surface 20 of the boards
4. These ink marks are deposited on the board in a pattern such as simple
geometrical objects
like triangles, squares or circles, or in more complex patterns such as
ornamental designs,
graphics, or distinctive lettering indicating product trade name or
manufacture. The number of
valves in the printhead determines whether the printhead is used to form ink
marks and patterns
or larger, more complex ornamental designs. Figure 1 shows a preferred
embodiment in which
a series of ink jet printheads 38 are supported on the mounting plate 35.
[0031] The present apparatus also includes a means for controlling the means
for
applying ink to apply the ink patterns on the boards that travel within the
predetermined space.
Although not required to be automated, it is preferred that control means is
coordinated by a
computer controller 44. The printer controller 44 is preferably programmed and
controlled
through user inputs provided through a key pad (not shown), touch screen (not
shown) or other
input device located on the exterior of the print controller housing. Another
suitable input
devices is a PC serially connected to the printer controller. An advanced
computer control
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interface unit, having a computer keypad, may be used to control and program
the printing of
particular patterns on the board 4.
[0032] Suitable ink jet heads and print controllers are custom-made or
modified from
readily available commercial sources. For example, the Matthews Corporation of
Pittsburgh,
Pa. produces ink jet systems under its Jet-a-Mark brand. These ink jet
systems use drop-on-
demand ink jet technology to form printed characters and graphics on the
board. The ink-jet
heads can contain either 16 valves (for forming simple patterns on a board) or
32 valves (for
forming more complex graphical patterns or distinctive lettering). A print
resolution of 6.25 to
32 dpi is capable with this system. A suitable computer controller is the Jet-
a-Mark R4 from
the Matthews Corporation of Pittsburgh, Pa.
[0033] The means for controlling the applying means may be done manually.
Thus, an
operator may manually control the movement of boards 4 into the predetermined
space 17 and
then manually initiate the application of ink onto the print surface 20 of the
board 4 to form
marks, patterns and designs. However, in order to increase the speed of the
marking process, as
well as the precision with which the marks are placed on the printing surface,
and to minimize
the amount of operator intervention, it is preferred that the control means be
automated.
[0034] In an automated and preferred process, the boards 4 are moved in the
selected
direction by the drive rollers 26 into the predetermined space. The drive
rollers 26 may be
powered and regulated by a synchronous drive ("timing") belt (not shown),
which
synchronizes the speed of each of the drive rollers 26 to maintain a
consistent speed at which
the boards are brought into the predetermined space. Typically the synchronous
drive belt is a
fiber-reinforced polymeric belt. The synchronous drive belt can improve the
printing precision,
and has the advantage over a gear/chain system, in that the gear/chain system
can stretch and
wear over time and fail suddenly and catastrophically.
[0035] A Variable Frequency Drive ("VFD") can be used to alter the speed of
the
boards as they travel in the selected direction and pass through the
predetermined space 17.
The "VFD" increases the speed of the panels as they are conveyed into the
predetermined space
17 so that they travel faster than the boards that have yet to enter the
predetermined space 17.
This ensures that a gap is formed between adjacent panels as they enter the
predetermined space
17 end-to-end, which allows the photo eye (discussed below) to differentiate
between two
adjacent panels and thereby initiate printing onto the boards at the correct
time. Preferably, a
minimum gap of about one inch is formed between adjacent panels.
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[0036] The present apparatus includes means for monitoring the movement of the
boards in the selected direction as they enter the predetermined space 17.
This monitoring
means informs the print controller 44 of the exact location of the board and
that the board is
about the enter the predetermined space, so as to initiate the printing
process. In controlling the
applying means, the print controller 44 takes into account the location of the
board, and the
speed at which the board is moving in the selected direction. Many different
suitable
technologies may function as the means for monitoring the movement of the
boards, but the use
of a photo eye is preferred.
[0037] Figure 1 shows a photo eye 53 placed below the level of the boards 4
for
detecting the movement of the boards in the selected direction into the
predetermined space 17.
The photo eye 53 is preferably a split-beam photocell utilizing a modulated,
narrow beam.
When the board crosses a beam emitted by the photo eye 53 (or other equivalent
monitoring
means), the photo eye 53 transmits a signal to the print controller 44
relaying the exact location
of the board, and initiates the printing process. A suitable photocell is a
modified Banner
Engineering Mini-beam SM312DSC, available from the Matthews Corporation with a
custom
fiber-optic extension (B6578-503-00). A custom-designed bracket for the photo
eye allows
positioning or calibration of print initiation to the leading edge of the
panel.
[0038] As the photo eye triggers the print controller to commence the printing
process,
the print controller also monitors the speed at which the boards 4 are moving
in the selected
direction so that the applying means can be properly controlled to form the
desired
combinations of patterns and graphics at the separate locations on the print
surface 20 of the
boards. Many different means may be used to measure the speed of the board,
but a preferred
means is the use of an encoder. In the embodiment shown in Figure 1, one of
the shafts 62 of a
drive roller is extended beyond the hold-down apparatus and a the rotary
encoder 56 mounted
directly to the portion of the shaft 62 of the drive roller 26 that extends
beyond the hold down
apparatus. The components for measuring the rotational speed of the rotary
encoder (an optical
reader, sensor or similar device, as discussed in detail below), are housed in
the box 59, but not
specifically shown. By mounting the encoder 56 on a shaft 62 extended beyond
the hold-down
apparatus, sawdust buildup on the encoder is prevented, and the distorting
effects of thermal
expansion reduced. The information gathered by the encoder 56 is transmitted
to the controller
44.
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[0039] Another alternative for installing of the encoder wheel makes use of a
set of
gears connected by a belt. In this installation (which is not illustrated in
the figures), a first gear
is mounted on the driver roller 26, and is mechanically connected by a belt to
a second gear,
which is mounted around an external shaft. The gears are given a proper ratio
with respect to
each other, so that the rotational speed of the external shaft has nearly the
same precise
rotational speed as the driver roller to which the first gear is mounted. The
encoder is then
attached to this external shaft. Because the encoder is located at some
distance from the
finishing line, both sawdust buildup and the distorting effects of changes in
the drive-roll
diameter are minimized.
[0040] The rotary encoder wheel 56 has indicia on its side and an optical
encoder
reader or sensor reads the indicia on the rotary encoder to provide a
positional or board velocity
signal to the print controller. As the rotary encoder is engaged by the drive
rollers 26 or as it
rotates around the drive rollers 26, a positional or velocity signal is
supplied to the controller 40
which coordinates the firing signals sent to the inkjet valves to direct the
ink droplets to print an
image according to the instructions provided by the operator through the print
controller.
[0041] The apparatus may also include other optional elements, such as means
for
treating the surface of the boards. These treating means include devices for
removing dirt or
other particles from the surface of the boards, as well as other devices such
as anti-static
equipment. In fig. 3 the means for treating the surface of the boards includes
an air knife 201 or
brush attached to the frame to remove dust from the print surface of the
boards 4. An air knife
applies a uniform flow of air across the print surface of the board to remove
particles or debris
from the print surface. Suitable air knives include the "Standard Air
KnifeT"", and the "Super
Air KnifeTM" from the Exair Corporation, Cincinnati, Ohio. Additionally, an
anti-static device
(such as shown as 222 in Figs. 1 and 3) may be attached to the support means
to dissipate static
electricity that builds up on the print surface after sanding OSB. Such static
electricity can
scatter ink droplets during printing, and this static electricity can also
pose an explosive hazard
at particular solvent concentrations and so it is highly desirable to remove
this static electricity.
"Tinsel bars" are suitable for this purpose. These bars consist of dangling
copper "tinsel"
secured to a rigid anodized aluminum holder connected to a ground. These
devices are
available from TAKK Industries, Inc. of Cincinnati, Ohio.
[0042] The present apparatus also preferably includes a lateral alignment
means for
aligning the boards with lateral edges of the frame. This lateral alignment
means is used so that
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the board is properly aligned along the lateral edges of the frame (shown as
items 204 and 207
in Fig. 3); this ensures that the board is properly aligned so that the ink
marks are placed on the
printing surface in the correct locations in order to from simple geometrical
shapes or more
complex patterns. In fig. 3, the lateral alignment means are the combination
of a left fence 210
and a right fence 213 that extend substantially parallel to each other.
Extending from the left
fence 210 are several leaf springs 216 which press against the lateral edge
204 of the board 14
to force the board against the right fence 213 to establish an accurate right
edge 207 reference
with the ink jet heads as the board 14 moves through the predetermined space
17.
[0043] If desired, another air knife 219 can be positioned on the far side of
the
predetermined space, beyond the ink applying means to accelerate the drying of
ink marks on
the surface of the boards subsequent to their passing through the
predetermined space 17. This
additional air knife may be selected from among the types of air knives
described above.
[0044] Any suitable ink for use on boards is suitable for use in the present
invention.
Preferably, the marking ink is a colorant (either a pigment or dye) suspended
or dissolved in a
solvent or continuous phase. The preferred continuous or solvent phase is an
alkyl ester, such
as ethyl acetate or ethyl butyl acetate. The colorant is preferably a mineral
material and the
colorant preferably has a sufficiently high molecular weight so that it does
not easily diffuse or
migrate through plasticized floor coverings such as vinyl linoleum. The
colorant may be used
to form colored patterns as discussed in Patent Application Serial No.
10/012,918, filed October
30, 2001, entitled "Boards Comprising an Array of Marks to Facilitate
Attachment", which is
hereby incorporated by reference. Preferably, the ink should be highly
resistant to fading
caused by ultraviolet light, and quick drying, with a drying time of between
about 1 to about 10
seconds. In addition to the colorant, the ink may also contain several other
ingredients such as
viscosity enhancing agents or thickeners, surfactants, polymeric binding
agents, opacifyers,
preservatives, optical brighteners, plasticizers, dispersing aids, coalescing
agents, and
defoaming agents.
[0045] A preferred ink is a dry black "non-settling" ink that is a suspension
of pigment
particles in a solvent phase of ethyl acetate. The viscosity of this black,
non-settling ink is 2.3
to 3.5 cps at 80 F. The ink has a drying time of about 5 to about 10 seconds.
[0046] As mentioned above, the ink may be applied to the print surfaces of
boards to
form marks, barcodes, date, crew designations, installation instructions or
other such
instructions, alphanumeric characters, and ornamental designs. The marks are
preferably
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CA 02492712 2005-01-07
grouped as arrays to identify locations where fasteners (not shown) can be
used to attach the
boards to a frame structure to form walls, roofs or floors. The marks on the
board may be
selected from several different forms including circles, dots, squares,
diamonds and other
suitable forms. The patterns which can be formed on the boards are described
in greater detail
in Patent Application Serial No. 10/012,918, entitled "Boards Comprising an
Array of Marks to
Facilitate Attachment", incorporated above.
[0047] Although the boards 4 can be made of any commonly used material, it is
preferred that the board be made from a wood or wood composite material, and a
preferred
wood composite material is OSB. Methods for making OSB, as well as suitable
OSB
compositions are well-known to those of ordinary skill in the art.
[0048] It will be appreciated by those skilled in the art that changes could
be made to
the embodiments described above without departing from the broad inventive
concept thereof.
It is understood, therefore, that this invention is not limited to the
particular embodiments
disclosed, but it is intended to cover modifications within the spirit and
scope of the present
invention as defmed by the appended claims.
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