Note: Descriptions are shown in the official language in which they were submitted.
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98P3CA
SCREEN PRINTING MACHINES
The present invention relates to screen printing machines and, more
particularly, to screen
printing machines in which printing platens are moved around an endless path
through
successive printing stations.
Screen printing machines of this type are known, for example, for printing T-
shirts, and such
machines usually comprise a plurality of printing stations, each provided with
a printing
screen, an inking and squeegee system for applying ink to the screen and a
platen alignment
system for locating the platens in position as the platens arrive, in
succession, at each printing
station.
In such machines, the platens are driven by means of an endless chain drive
mechanism
around their endless path on a machine bed. The alignment of each platen at
each printing
station has been effected by means of an alignment mechanism applying force to
the platens
in a direction extending transversely of the path of travel of the platens.
This has the
disadvantage that the force exerted by this alignment mechanism tends to force
components
of the machine frame at opposite sides of the path of travel apart from one
another, thus
adversely affecting the accurate positioning of the platens at the printing
station during
printing operations.
More particularly, the frames of screen printing machines are normally
constructed of frame
components which are bolted together and which, consequently, tend to flex out
of shape
when subjected to forces tending to urge the frame components apart from one
another.
However, for accurate printing at successive printing stations, it is
necessary to ensure that
each platen is accurately located in position during each printing operation.
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In prior art printing machines, as each platen arrives at a printing station,
it is pushed so as
to slide horizontally, in a direction transverse to the path of travel of the
platen, to urge a
drive chain, provided for displacing the platen around the path, into abutment
with a rail in
order to register the platen for printing.
Since each ofthe platens is simultaneously forced so as to slide against
friction into abutment
this way, and since the forces acting on the platens are exerted transversely
of the path of
travel of the platens, the machine frame is thus subjected to these forces, at
various positions,
and consequently the components of the machine frame are deflected, thus
adversely
affecting the accuracy of the registration of the platens.
According to the present invention, there is provided a screen printing
machine comprising
a drive mechanism operable to displace printing platens along an endless
horizontal path
extending through successive printing stations, and a platen alignment
mechanism is
provided at each printing station which comprises a locating member mounted
for vertical
to-and-fro movement between a first position in which the locating member
engages a platen
support carrying a respective one of the platens, and a second position, in
which the locating
member is spaced from the platen support.
In a preferred embodiment of the invention, the locating member comprises a
vertically
displaceable bar provided, at opposite sides, with V-shaped recesses, and the
platen support
is provided with locating rollers which are spaced apart to receive the bar
therebetween and
which have V-shaped formations shaped for interengagement with the V-shaped
recesses of
the bar.
With this platen alignment mechanism, each platen can, in succession, be
accurately located
in position at the respective printing station, by vertical displacement of
the alignment bar
into interengagement with the locating rollers of its platen support.
Consequently, no forces
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are exerted on the platens or on other parts of the machine which act in a
direction transverse
to the endless horizontal path.
The preferred embodiment of the present invention also includes a screen
loading and
unloading mechanism at each printing station, the screen loading and unloading
mechanism
including screen holders which are engageable with opposite sides of a
printing screen. Each
of the screen holders comprises a screen support which is mounted for
pivotation to and fro
between a first position, beneath the screen, and a second position, removed
from the screen.
An adjustment mechanism is operable to adjust the positions of the screen
holders and,
thereby, to correspondingly adjust the position of the screen. For this
purpose, the screen
holder and the screen have mutually engageable locating formations, and the
adjustment
mechanism is operable to adjust the position of the locating formations of the
screen holders
and, thereby, to correspondingly adjust the position of the screen on
interengagement of the
locating formations of the screen and the screen holder.
This adjustment mechanism comprises independently actuatable members for
adjustably
displacing the locating formation of one of the screen holders in mutually
orthogonal
horizontal directions.
The screen holders are also provided with screen clamping devices, which each
comprise a
clamp movable into a clamping position for engaging the screen between the
clamp and the
screen support, and an actuator which is operable to displace the clamping
devices to and
from their clamping positions.
The screen printing machine according to the present invention includes
printing heads
spanning the path of travel of the platens at each printing station and
carrying the printing
screens and a lifting system for simultaneously lifting opposite ends of the
printing heads.
The lifting system comprises a prime mover and a belt and pulley system
connected to be
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driven by the prime mover, the belt and pulley system comprising pairs of
horizontally
spaced, vertically extending belts at opposite sides of the endless path,
connections being
provided between each of the belts and the printing head supports on which the
printing
heads are mounted.
The present invention will be more readily understood from the following
description thereof
given, by way of example, with reference to the accompanying drawings, in
which: -
Figure 1 shows a plan view of a screen printing machine according to the
present invention;
Figure 2 shows a view taken in transverse cross-section through the printing
machine along
the line 2-2 of Figure 1;
Figure 3 shows, on an enlarged scale, a view of parts of the apparatus shown
in Figure 2;
Figure 4 shows a partly-exploded view of a printing screen frame and
components of
adjustment mechanisms for adjustment of the position of the printing screen;
Figure 5 shows a broken-away view, on an enlarged scale, of parts of the
apparatus of Figure
3;
Figure 6 shows a partially broken-away view, in perspective of one of the
screen adjustment
mechanisms of Figure 4;
Figures 7 and 8 show, respectively, a plan view and a view in vertical cross-
section through
parts of the screen adjustment mechanism of Figure 1;
Figure 9 shows a view in vertical cross-section through parts of a screen
adjustment
mechanism of Figure 3;
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Figure 10 shows a view, in perspective, of components of another screen
adjustment
mechanism of Figure 3;
Figure 11 shows a view in perspective of a jig for use in loading and
unloading printing
screens in the machine of Figure 1;
Figure 12 shows an underneath plan view of parts of a belt and pulley lifting
system of the
machine of Figure 1;
Figure 13 shows a view inside elevation of the belt and pulley mechanism of
Figure 12;
Figure 14 shows a view, taken in section transversely of the machine of Figure
1 and
illustrating parts of the lifting system;
Figure 15 shows a view, partially in vertical cross-section, of a locking
mechanism;
Figure 16 shows a view taken in cross-section transversely of the machine of
Figure 1 in a
direction opposite to that of Figure 14;
Figure 17 shows a broken-away view, in perspective, of components of a platen
alignment
mechanism forming part of the printing machine of Figure 1;
Figure 18 shows a broken-away view, in perspective, of components shown in
Figure 17 and
additional components of the platen alignment mechanism; and
Figure 19 shows a view taken in transverse cross-section through a squeegee
holder and an
associated squeegee forming parts of the printing machine of Figure 1.
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The printing machine shown in Figure 1, which is indicated generally by
reference numeral
10, has twelve platens 12 which, in operation of the screen printing machine
10, are driven
around a horizontal endless path by means of a drive chain 14 and a pair of
sprockets 16
engaging the drive chain 14, one of the sprockets 16 being driven by a
servomotor 15. It is,
however, pointed out that the present invention may be embodied with more
than, or fewer
than, twelve platens.
The platens 12 are carried on platen supports in the form of platen support
arms 18 which
are supported, at their inner and outer ends, on inner and outer endless
tracks 20 and 22 (see
Figure 3), provided on a machine frame indicated generally by reference
numeral 24 in
Figure 3. At opposite ends of the machine, the track 22 is interrupted, and
the platen support
arms 18 are supported by a curved track 23 underlying the platen support arms
18 and a
curved retainer rail 25 overlying the platen support arms 18, the track 23 and
the rail 25 being
provided at the inner side of the path of travel of the platens 12.
The endless path of movement of the platens 12 extends through six printing
stations,
indicated generally by reference numerals 26, at which screen frames 28 are
provided, as
described in greater detail below, for use in screen printing.
In operation of the screen printing machine 10, the platens 12 are moved
around their endless
path with an intermittent motion, so that each platen 12 is temporarily
located in succession
at each of the printing stations 26 to enable a printing operation to be
effected at each
printing station.
Turning now to Figures 2 and 3 of the accompanying drawings, each printing
station 26 is
equipped with pivotable printing heads, two of which are indicated,
respectively, by
reference numerals 30a and 30b in Figure 2, spanning the path of travel of the
platens 12.
These printing heads are similar in construction to one another and,
therefore, only one of
them will be described in further detail in the present specification.
CA 02217358 2001-05-03
As shown in Figure 2, the printing head 30a has been pivoted into a raised
position, whereas
the printing head 30b is in a lowered position.
More particularly, the printing head 30a is vertically pivotable about a
horizontal pivot 32
by the action of a pneumatic piston and cylinder device 34, which is connected
between the
machine bed 24 and the lower end of an arm 36 depending from one end of the
printing head
30a.
One of the screen frames 28 is illustrated in greater detail in Figure 4, from
which it can be
seen that this screen frame 28 comprises four rollers 40 connected in a
rectangular array by
corner connectors 42, the frame also including, at opposite ends thereof, a
pair of
reinforcement rails 44, each of which is formed with a frame alignment opening
46 and a
further hole 47 employed, as described below, for loading and unloading the
printing screen
28.
The screen holder 38 will now be described with reference to Figures 4 through
8. As shown
in greater detail in Figure 3, the printing head 30a has two screen holders
indicated generally
by reference numerals 38 and 39, which are described in greater detail below.
As shown in Figures 5 and 6, the screen holder 38 comprises a pair of lever
arms 48 which
are pivotable, in a vertical plane, about a horizontal pivot 50. The arms 48,
as shown in
Figure 6, carry a mounting plate 52 and a lower plate 53. A frame support bar
54 is
adjustably connected to the mounting plate 52 and the lower plate 53, and is
provided with
a screen locating formation in the form of a bevelled locating pin 56
extending upwardly
from the support bar 54. This locating pin 56 is engageable in a corresponding
one of the
CA 02217358 1998-12-17
_$_
alignment holes 46 of the screen frame 28, which hole serves as a locating
formation for
locating the latter in position.
By means of a pneumatic piston and cylinder device 58 (Figure 5), connected
between the
printing head 30a and a rod 59 connecting the bars 48, the latter can be
pivoted about pivot
50 to move the support bar 54 from the position in which it is shown in Figure
5 into a
position (not shown) in which it underlies the reinforcement rail 44 of the
screen frame 28
and in which the alignment pin 56 is located vertically below the alignment
opening 46.
In this operative position of the support bar 54, a pneumatic piston and
cylinder device 60
can be activated to move a clamp 62 downwardly into pressing engagement with
the
reinforcement rail 44 so as to thereby clamp the reinforcement rail 44 between
the clamp 62
and the support bar 54. The piston and cylinder device 60 and the clamp 62
thus form parts
of a clamping device for clamping engagement with the printing screen 28. In
this way, the
screen frame 28 is accurately located in position at its printing station.
This position of the screen frame 28 can be manually adjusted by adjustment of
the support
bar 54 and its alignment pin 56.
The support bar 54 is connected, at opposite ends, to arms 64 and 66 (Figures
6, 7 and 8).
The arm 64 is connected by means of a connecting rod 68 to an adjustment knob
70. More
particularly, the connecting rod 68 is pivotably connected at one end, by
means of a pivot
connection 72, to the arm 64 and, in addition, is eccentrically pivotably
connected, at its
opposite end, by means of an eccentric pivot 74 to the adjustment knob 70. By
manual
rotation of the adjustment knob 70, therefore, the support bar 54 can be
horizontally
adjustably displaced, to and fro, in the direction of double-headed arrow A1.
To allow this
movement, the lower plate 53 is formed with a slot 71 and the pivot 62 extends
through a
slide member 73 which is slidable to and fro along the slot 71.
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As shown in Figure 9, the knob 70 is provided with a spring-biased detent 75
which engages
in detent recesses (not shown) in the upper surface of a circular flange 77 of
a sleeve 79
secured to the plate 52, and the knob 70 is secured by a screw 81 to a
vertical shaft 83
eccentrically connected to the arm 68 by the eccentric pivot 74.
The arm 66 is connected, by means of a pivot connection 76, a connecting rod
78 and an
eccentric pivot connection 80, to a manually adjustable knob 82, by means of
which the arm
66 and, therewith, the support bar 54 can be adjusted to and fro as indicated
by double-
headed arrow A2 in a direction orthogonal to that of arrow A1.
The opposite end of the screen frame 28 is supported on the screen support 39,
components
of which are shown in Figures 4 and 10.
The screen holder 39 has a screen support bar 54a, which is provided with an
upstanding
alignment pin 56a (Figure 4), corresponding to the pin 56 of Figure 4, for
engagement in the
alignment hole 46 at the innermost end of the screen frame 28. The support bar
54a is
carried on a mounting plate 53a, which is suspended by the lower ends
ofpivotable arms 48a,
for pivotation to and fro, between an operative position beneath the screen
frame
reinforcement strip 44 and an inoperative position spaced from the screen
frame, by means
of pneumatic piston and cylinder device 58a (Figure 3) connected between the
printing head
30a and the arms 48a.
The support bar 54a and, therewith, the alignment pin 56a are adjustable to
and fro, as
indicated by double-headed arrow A3, by means of a manual adjustment knob 84,
which is
rotatably mounted on a component 85 of the machine frame 24. An endless belt
86 connects
the knob 84 to a vertical rod 88 which, at its lower end, is connected by an
eccentric pivot
90 for longitudinally displacing a connecting rod 92, which in turn is
connected by a
pivot connection 94 to an arm 96 extending from the support bar 54a. In this
way, the
screen support bar 34a and its alignment pin 52a can be adjusted to and fro as
indicated by
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double-headed arrow A3. Movements in the direction of arrow A4 occur in
response to
adjustment of the printing screen by the knob 82 of Figure 6.
The pivotable arms 48a also carry a mounting plate 52a, on which are mounted a
pair of
clamping devices which have pneumatic piston and cylinder devices 60a and
which are
similar to the clamping devices of Figure 5, comprising the piston and
cylinder devices 60
and the clamp 62, and an additional clamping device comprising a pneumatic
piston and
cylinder device 63.
Figure 11 shows a temporary screen support, which is indicated generally by
reference
numeral 98 and which is for use in automatically loading and unloading the
printing screens
28 to and from the printing machine 10.
The screen support 98 comprises a jig having, at opposite ends, transverse
arms 99, which
are connected by an elongate intermediate portion 100. Each arm 99 has, at one
end, an
upstanding locating pin 101 and, at its opposite end, an upwardly facing
abutment 102.
The screen support 98 can be fastened to any one of the platen support arms
18, in place of
its platen 12, and then serves to carry one of the printing screens 28 to and
from its printing
station 26, at which the screen is automatically loaded onto or unloaded from
the respective
printing head 30 or 30a, as described below. For this purpose, the locating
pins 101 of the
temporary screen support 98 are engaged in the holes 47 of the reinforcement
rails 44 (Figure
4) of the printing screen, while the abutments 102 engage and support the
undersides of the
reinforcement rails 44. The arms 99 of the temporary screen support 98 can
then carry the
printing screen to its printing station 26 in a manner such as to allow the
printing screen to
be engaged by the screen holders 38 and 39 and then upwardly removed from the
temporary
support by raising of the respective printing head as described below.
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Likewise, by reversing these operations, this printing screen can be deposited
from the
printing head onto the temporary screen support by lowering the printing head,
and then
released by the screen holders 38 and 39, to allow the printing screen to be
carried from its
printing station to one end of the printing machine 10 for unloading the
screen.
A printing head lifting system, illustrated in Figures 12 through 16, is
provided for raising
and lowering the printing head 30a and comprises a prime mover, in the form of
a stepping
motor 110, which, through a pulley and belt connection 111, rotates a nut 113
in threaded
engagement with a worm shaft 115 and thereby longitudinally displaces the
latter. The worm
shaft 115 is connected by a horizontal belt 112 to a pair of pulleys 114. The
pulleys 114 are
fixed to parallel horizontal shafts 116, which are rotatably secured to the
machine frame 24
and which, at their ends, carry pulleys 118. Two pairs of vertically extending
endless belts
120, located at the inner and outer sides, respectively, of the path of travel
of the platens 12,
extend upwardly from the pulleys 118 to upper pulleys 122.
The two endless belts 120, of each pair, are interconnected by a cross-piece
124, 124a
(Figures 14 and 16), which are movable to and fro vertically and
simultaneously, by means
of the endless belts 120, the vertical movement of the cross-pieces 124 being
guided by
means of guide rods 126, 126a secured to the machine frame 24.
The cross-pieces 124, 124a each support a pair of horizontally spaced,
vertical rods 128,
128a, which are slidably guided by means of guide sleeves 130, 130a supported
on housings
131 and 131 a on the machine frame 24, two of the rods 128 being connected, at
their upper
ends and at the outer side of the path of travel of the platens 12, to a
locking device indicated
generally by reference numeral 140 in Figure 14 and illustrated in greater
detail in Figure 15,
which serves to lock the printing head 30a to the cross-piece 124. The locking
device 140
has a pair of oppositely operating piston and cylinder devices 142 and 143
(Figure 15), which
are housed in a cylindrical housing 144 and which serve to displace to and fro
a pair of
oppositely directed locking pins 146 and 147. The pins 146 and 147, on
extension of their
CA 02217358 1998-12-17
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pneumatic piston and cylinder devices 142 and 143, engage in recesses 149 and
150 in blocks
152.
As can be seen from Figure 15, the pneumatic piston and cylinder device 143 is
of larger
cross-section than the pneumatic piston and cylinder device 142. Consequently,
the piston
and cylinder device 143 will exert a greater force than the piston and
cylinder device 142
and, thus, will ensure that the block 152 at the left-hand end of the housing
144, as viewed
in Figure 15, will act as an abutment which will always be forced into
abutment with a
counter-abutment bushing 155 on the housing 144 on extension of the piston and
cylinder
devices 142 and 143. Since the housing 144 is fixedly connected to the
printing head, this
ensures that the locking device 140 serves to accurately position and retain
the printing head
relative to the machine frame 24.
At the inner side of the path of travel of the platens 28a, the rods 128a
support a pivot
connection, indicated generally by reference numeral 134, which includes a
pivot shaft 135
secured at its ends to blocks 136 carried on a mounting bar 137, supported on
the rods 128a,
and a cylindrical sleeve 138 which is co-axially and rotatably mounted on the
pivot shaft by
bearings 139 and forms part of the printing head 30a.
On release of this locking device 140, the printing head can be pivoted about
the pivot shaft
135 by operation of the piston and cylinder device 34 (Figure 3) so as to
raise the printing
screen to provide access to the underside of the screen for cleaning, and
other maintenance
and inspection purposes.
With the printing head lowered and locked by the locking device 140, the
printing head
lifting system of Figures 12 through 16 is employed for raising the printing
head as each
platen 28 arrives at the respective printing station 26 and lowering the
printing head to lower
the respective printing screen 28 into position for printing.
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Also, the printing head lifting system is employed to raise and lower the
printing head during
loading and unloading of the printing screen to and from the printing head as
described
above.
Figure 17 and 18 illustrate the components of a platen alignment mechanism for
accurately
positioning the platen arms 18 at the printing stations 26.
As shown in Figures 17 and 18, one end of the platen support arm 18 carries,
at its underside,
a vertical plate 160, on which first locating members in the form of a pair of
rollers 162 are
mounted so as to be freely rotatable about respective horizontally spaced
horizontal axes.
This end of the platen support arm 18 is mounted on a transverse plate 161, to
the underside
of which is secured a block 163 of low friction plastic material, which
slidably supports the
platen support arm 18 for movement along the rail 20.
The plate 161 has been shown broken-away in Figure 18 to facilitate
illustration of
components beneath the plate 161.
Two further pairs of rollers 164 are freely rotatably mounted on a roller
support plate 166
which is, in turn, secured to the machine frame 24. The rollers 164 have V-
shaped
peripheries which engage in correspondingly V-shaped recesses 168 at opposite
vertical sides
of a second locating member in the form of a vertical bar 170.
The bar 170 is vertically movable, to and fro, and the rollers 164 are guide
rollers which are
in guiding engagement with the bar 170 and guide this vertical movement of the
bar 170 and
which retain the bar 170 against horizontal displacement.
Guided by the rollers 164, the bar 170 can be raised into a first position, in
which it is located
between and in engagement with the rollers 162, and lowered into a second
position, in
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which it is shown in Figure 17, and in which it is spaced from the rollers 162
and the other
components of the platen support arm 18.
The rollers 162 have V-shaped peripheries for rolling engagement with the
recesses 168 in
the opposite sides of the bar 170, so that on displacement of the bar 170
upwardly into its
first position, the bar 170 accurately determines the horizontal location of
the respective end
of the platen support arm 18. More particul;~rly, due to the interengagement
of the V-shaped
roller peripheries and bar recesses, the bar 170 accurately positions the
platen support arm
18 both longitudinally of the arm 18, i. e. in a first direction extending
transversely of the
path of travel of the platens 12, and also transversely of the arm, i. e.
longitudinally of that
path in a second direction at right angles to the first direction. The rollers
162 are adjustable
relative to their plate 160, and the plate 160 is adjustably mounted on a
support plate 167
forming part of the machine frame 24.
The opposite end of the platen support bar 18, as illustrated in Figure 18, is
located in
position by a locating mechanism, indicated generally by reference numeral
172, which
comprises a locating member in the form of an arm 174 having, along its
length, a
downwardly convergent V-shaped underside which is engageable in an upwardly
open,
correspondingly V-shaped recess 176 in the platen support arm 18.
The arm 174 is mounted at the upper end of a bar 178 which is vertically
displaceable, to and
fro, by means of a pneumatic piston and cylinder device 180, the movement of
the bar 178
being guided by means of two pairs of guide rollers 182, which engage opposite
vertical
sides of the bar 178 and only two of which are shown in Figure 17. Thus, the
underside of
the arm 174 is a V-shaped downwardly directed protrusion formation which is
snugly
engageable in the correspondingly V-shaped upwardly open recess formation of
the recess
176.
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For effecting this relative movement of the vertical bar 170 and the rollers
162, there is
provided an actuating device mechanism comprising a pneumatic piston and
cylinder device
184 connected between the machine frame 24 and a crank arm 185 on a shaft 186
journaled
in the machine frame 24. A further crank arm 187 on the shaft 186 and a link
188 connect
the shaft 186 to the vertical bar 170.
Figure 19 shows a squeegee holder indicated generally by reference numeral
190. This
squeegee holder 190 comprises a squeegee support bar in the form of an
extrusion 192,
which is formed with a recess 194 at its underside, and with a cylindrical
passage 196
adj acent its top, the passage 196 being open to the exterior of the extrusion
192 through a gap
198.
A pair of clamping strips 200, which are urged towards one another into
clamping
engagement with a squeegee blade 202 by means of screws, one of which is
indicated by
reference numeral 204, are each formed with an upper edge having a lateral
projection 206.
Elongate retainer 210, formed as an extrusion, extends longitudinally of the
squeegee holder
190 and has, along its underside, a laterally projecting edge portion 212. As
can be seen in
Figure 19, the lateral projections 206 of the two clamping strips 200 are
engaged,
respectively, by this projecting edge portion 212 and by a longitudinal
projection 214 on the
extrusion 192. In this way, the clamping strips 200, which together with the
squeegee blade
202 form a squeegee 207, are retained in the recess 194 and, thus, are secured
relative to the
squeegee holder 190.
The elongate retainer 210 is formed with a further lateral projection 216,
which is engaged
in a recess 218 extending longitudinally of the extrusion 192 at one side of
the extrusion 192.
The projection 216 and the recess 218 are shaped and dimensioned so as to
allow the
projection 216 to rock or pivot to and fro, about an axis (not shown)
extending longitudinally
of the squeegee holder 190 in order, thus, to allow the projecting edge
portion 212 of the
elongate retainer 210 to be moved to and fro, relative to the extrusion 192,
into an operative
CA 02217358 1998-12-17
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position, in which it is shown in Figure 19 and in which the projecting edge
portion 212 is
located near the recess 194 for releasibly engaging and retaining the squeegee
207 relative
to the extrusion 192, and a released position, in which the projecting edge
portion 212 is
disengaged from the projection 206 of the left-hand clamping strip 200, as
viewed in Figure
19, so as to thus release the squeegee 207 from the squeegee holder 190.
The squeegee holder 190 also includes an actuator device comprising an
elongate inflatable
tube 220 which extends longitudinally of the extrusion 192 and which can be
inflated by
compressed air from a compressed air supply 221. The elongate retainer 210
includes a
further longitudinal, laterally proj ecting portion 222, which extends
laterally of the elongate
retainer 210 into engagement with the inflatable tube 220. More particularly,
the tube 220
is received within, and extends longitudinally of, the passage 196, and the
projecting portion
222 extends through the gap 198, which extends longitudinally of the extrusion
192, into
engagement with the tube 220. It will be apparent that, on inflation of the
tube 220, the
elongate retainer 210 is rocked or pivoted in an anti-clockwise direction, as
viewed in Figure
19, so as to urge the proj ecting edge portion 212 into its operative
position, i.e. into retaining
engagement with the respective projecting edge portion 206 of the squeegee.
Figure 19 also shows a view in cross-section through a flood bar holder 190a
comprising an
extrusion 192a which is identical to the extrusion 190 of the squeegee holder
190, the
extrusion 192a being equipped with an elongate retainer 210a identical to the
elongate
retainer 210 but facing in an opposite lateral direction from that of the
extrusion 192. The
elongate retainer 210a releasibly retains a flood bar 230 relative to the
squeegee holder 190a
in a manner which, as is readily apparent, is closely analogous to the above-
described
retention of the squeegee relative to the squeegee holder 190.
The squeegee holder 190 and the flood bar holder 190a are moved to and fro
across the
respective printing screen by a suitable mechanism, as disclosed in United
States Patent No.
CA 02217358 2001-05-03
-17-
5,626,074, issued May 6, 1997.
As will be apparent to those skilled in the art, various additions and other
modifications may
be made to the above-described apparatus within the scope and spirit of the
appended claims.
