Reinforced hose means for biasing a squeegee

A screen printing machine wherein a hollow cylindrical stencil rotates about a stationary but adjustable horizontal header which supplies a liquid and is welded to a carrier for a reciprocable or pivotable holder supporting a blade-like or rod-like squeegee. The latter is biased against the internal surface of the stencil by a deformable tubular cushion which is received in a U-shaped portion of the carrier and is deformed by an elongated extension of the holder which imparts to the cushion a kidney-shaped cross-sectional outline. The cushion can be bonded to the carrier and comprises an elastic hose which is reinforced by one or more textile or metallic layers or a non-elastic hose which is reinforced by one or more layers of elastomeric material.

BACKGROUND OF THE INVENTION 
The present invention relates to screen printing machines in general, and 
more particularly to improved mounting and biasing means for a squeegee 
which is installed in the interior of a cylindrical or bandlike stencil in 
a screen printing machine. 
It is already known to mount a blade-like or rodlike squeegee in a holder 
which is biased in a direction toward the internal surface of the stencil 
by a gas-filled cushion. As a rule, the cushion consists of rubber or 
rubber-like synthetic plastic material so that it can undergo deformation 
as well as expansion and contraction. This affects the uniformity of 
pressure which the cushion transmits to the holder because the length of 
the cushion changes with changes is the pressure of entrapped fluid. 
Furthermore, the cushion is subjected to considerable wear because it 
slides along the adjacent surfaces of the holder and the carrier means 
whenever it expands or contracts. If the cushion cannot slide relative to 
the adjacent parts, the pressure in its interior varies due to varying 
thickness of its wall which also affects the quality of the printing 
operation, especially as regards the uniformity of pressure with which the 
squeegee is urged against the internal surface of the stencil. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide a novel and improved device which 
biases the holder and the squeegee in a screen printing machine toward the 
internal surface of a cylindrical or band-like stencil. 
Another object of the invention is to provide a device which biases the 
holder and the squeegee with an accurately reproducible and accurately 
regulatable force along the full width of the material which is being 
treated by the stencil. 
A further object of the invention is to provide a novel and improved 
deformable tubular cushion for use as a means for biasing the squeegee 
against the internal surface of the stencil. 
An additional object of the invention is to provide a screen printing or 
analogous machine which embodies the improved biasing device and to 
provide the machine with a novel holder for the squeegee and with novel 
support means for the holder and the biasing device. 
Still another object of the invention is to provide a screen printing 
machine wherein the squeegee is biased against the stencil with an 
accurately reproducible and regulatable force even if the width of the 
material is to be treated is in the range of up to and in excess of five 
meters. 
The invention is embodied in a screen printing or like machine which 
comprises an elongated liquidpermeable stencil having endless internal and 
external surfaces, means for moving the stencil so as to engage successive 
increments of the external surface with successive increments of a web of 
material to be treated, stationary support means in the interior of the 
stencil, an elongated holder which is movably mounted in the support 
means, a blade-like or rod-like squeegee which is mounted in the holder, 
and novel and improved biasing means interposed between the holder and the 
support means to urge the squeegee against the internal surface of the 
stencil, preferably at or close to the locus where the external surface of 
the stencil contacts the web. The biasing means comprises an elongated 
tubular gas-filled cushion which is resiliently deformable but cannot 
expand or contract. The holder has an elongated extension which bears 
against and depresses a portion of the cushion; this extension preferably 
cooperates with a substantially U-shaped portion of the support means to 
impart to the cushion a substantially kidney-shaped cross-sectional 
outline. If the stencil is horizontal, the cushion is preferably located 
above the holder and below the support means so that the extension of the 
holder depresses the lower portion of the cushion. 
The cushion may comprise a hose of elastomeric material and one or more 
reinforcing layers of steel, another metal and/or fabric which are 
embedded in the material of the hose. It is also possible to use a 
flexible but non-stretchable hose and to employ one or more elastomeric 
reinforcing layers which are embedded in the material of the hose. A 
portion of the cushion may be glued or otherwise bonded to a portion of 
the support means. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved screen 
printing machine itself, however, both as to its construction and its mode 
of operation, together with additional features and advantages thereof, 
will be best understood upon perusal of the following detailed description 
of certain specific embodiments with reference to the accompanying 
drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring first to FIGS. 1 to 4, there is shown a portion of a screen 
printing machine which comprises a rotary horizontal cylindrical screen or 
stencil 1. The lowermost portion of the external surface of the stencil 1 
contacts a web 2 of fabric or other material to be printed. The fabric is 
moved in the direction indicated by arrow and is preferably advanced 
together with a suitable back cloth, not shown, which travels above a 
stationary counterpressure beam G of the type disclosed, for example, in 
my copending application Ser. No. 479,911 filed June 19, 1974, now U.S. 
Pat. 3,988,985. The cylindrical stencil 1 can be replaced by an endless 
band-like stencil which is trained over at least two rolls, preferably 
over at least three rolls at least one of which is driven and at least one 
of which constitutes a tensioning means for the band. 
The stationary support means for the pivotable holder 7 of a blade-like 
elastically deformable squeegee 8 comprises a horizontal fluid-supplying 
pipe or header 3 and a carrier 4 which is welded or otherwise rigidly 
secured to the pipe 3 in the interior of the stencil 1. 
The pipe 3 can supply into the stencil 1 a highly viscous (pasty) or 
readily flowable liquid substance, e.g., an adhesive or a coloring agent. 
As shown in FIG. 4, the top portion of the pipe 3 has at least one port 3a 
which discharges the liquid against the internal surface of a baffle-like 
deflector 3b. 
The carrier 4 is located at a level below the tube 3 and includes a 
substantially U-shaped wall or portion 42 having two downwardly extending 
legs and a concave underside serving as an abutment for the adjacent 
portion of an elongated tubular cushion or biasing means 5 which is filled 
with a compressed gas (e.g., air) and serves to urge the holder 7 
downwardly, as viewed in FIG. 4, whereby the edge portion 8A of the 
blade-like squeegee 8 bears against the internal surface of the stencil 1 
with a force which is proportional to the pressure of gaseous fluid in the 
cushion 5. The means for holding the cushion 5 against movement out of the 
socket which is defined by the portion 42 of the carrier 4 includes two 
abutments or shoulders 40 which extend toward each other at the lower ends 
of the respective legs and may constitute horizontal ledges forming 
integral of separable parts of the carrier. If desired, the upper sides of 
the shoulders 40 can be configurated to conform exactly to the shape of 
the adjacent portion of the external surface of the cushion 5. The cushion 
5 extends along the full length of the beam G and its ends are sealed save 
for the ports which serve for admission or evacuation or compressed gas. 
The upper portion of the external surface of the cushion 5 can be glued or 
otherwise bonded to the concave surface of the carrier portion 42. 
The carrier 4 further comprises several (e.g., two) laterally extending 
brackets or fins 41 which support a pintle G extending in parallelism with 
the axis of the stencil 1 and with the edge portion 8A of the squeegee 8. 
The pintle 6 may constitute a one-piece shaft or it may consist of two or 
more discrete coaxial sections each of which is preferably mounted in at 
least two brackets 41. It will be noted that the pintle 6 is located 
behind the squeegee 8, as considered in the direction of rotation of the 
stencil 1 (see the arrow D in FIG. 4). 
The holder 7 for the squeegee 8 is pivotable about or with the pintle 6 and 
comprises a first portion 71 which is directly mounted on the pintle 6, a 
second portion 72 which supports the squeegee 8, and screws, bolts or 
analogous fasteners 73 for rigidly but separably connecting the portion 72 
to the portion 71. FIG. 4 shows that the portions 71, 72 have 
complementary (mating) parts 71A, 72A which are in face-to-face abutment 
with each other and that the parts 71A, 72A have aligned external surfaces 
71B, 72B which merge into each other to insure a smooth transition from 
the portion 71 into the portion 72 or vice versa. If desired, the 
one-piece portion 71 of the holder 7 can be replaced by two or more 
discrete elements which are spaced apart from each other, as considered in 
the axial direction of the pintle 6, and each of which is separably 
attached to the portion 72. For example, the portion 71 of the holder 7 
may comprise a discrete element for each bracket 41 of the carrier 4. The 
portion 72 of or the entire holder 7 may consist of a suitable synthetic 
plastic material, e.g. nylon. Such a possibility is shown in FIG. 9 which 
resembles FIG. 4 but shows at least the portion 72 may be of synthetic 
plastic material. The arrow Y indicates that the holder 7 can move 
relative to the carrier 4 by reciprocating. 
Those parts of the portion 72 of the holder 7 which are remote from the 
pintle 6 carry one or more eyelets 74 for the lower end portions of 
vertical helical springs 75 which serve to bias the holder and the 
squeegee 8 counterclockwise, as viewed in FIG. 4, i.e., to urge the edge 
portion 8A away from the internal surface of the stencil 1. The bias of 
the springs 75 is preferably selected in such a way that they counteract 
the combined weight of the holder 7 and squeegee 8 so that the force with 
which the edge portion 8A bears against the stencil 1 is determined 
exclusively or practically exclusively by the pressure of gaseous fluid 
which is confined in the deformable but non-stretchable cushion 5. The 
eyelets 74 may be formed with externally threaded shanks which extend into 
tapped bores of the portion 72. The upper end portions of the spring 75 
are attached to retainers 3d on the pipe 3; however, it is also possible 
to provide such retainers on the upper portion of the carrier 4. 
The cross section of the squeegee 8 is T-shaped and the head 80 of this 
squeegee extends into a mating groove 76 provided in the underside of the 
holder portion 72. However, it is equally within the purview of the 
invention to employ a rod-like cylindrical squeegee 8a of the type shown 
in FIG. 4a; the major portion of the squeegee 8a is received in a 
complementary elongated socket 76a provided in a modified holder portion 
72a. 
Referring again to FIGS. 1 to 4, the portion 72 of the holder 7 comprises 
an upwardly projecting elongated extension or rail 77 which is bounded by 
a rounded (substantially semi-cylindrical) surface and bears against the 
underside of the deformable cushion 5 so as to impart to the cushion a 
kidney-shaped cross-sectional outline. The axis of the pintle 6 and the 
axes of the shanks of eyelets 74 are preferably located in a common 
horizontal plane which extends substantially midway between the cushion 5 
and the squeegee 8. Also, the extension 77 and the squeegee 8 preferably 
have a common vertical symmetry plane which includes the axis of the tube 
3 and is normal to the plane of the web 2 in the region where the web is 
contacted by the external surface of the stencil 1. Since the squeegee 8 
is located substantially or exactly midway between the pintle 6 and the 
springs 75, its downwardly extending part can be located in a vertical 
plane when the edge portion 8A is not deflected by the internal surface of 
the stencil 1; this insures that the extent of deflection of the edge 
portion 8A from such vertical plane can be regulated by the simple 
expedient of changing the pressure of fluid in the cushion 5. Such 
mounting of the holder 7 further insures that the squeegee 8 is not likely 
to vibrate, oscillate or perform other stray movements when the screen 
printing machine is in use. The rounded upper surface of the extension 77 
reduces the likelihood of damage to the cushion 5 and enables the latter 
to lie flush against the concave surface of the U-shaped portion 42 of the 
carrier 4. This insures that the upper part of the external surface of the 
cushion 5 is not likely to shift relative to the concave surface of the 
portion 42 when the extension 77 moves up or down in response to changes 
in the pressure of fluid which is entrapped in the interior of the 
cushion. Of course, the cushion 5 cannot move relative to the portion 42 
if it is glued or otherwise bonded to the carrier 4. 
When the cushion 5 receives additional compressed gas, it tends to reduce 
the depth of depression which is caused by the extension 77, i.e., the 
holder 7 is urged to pivot counterclockwise, as viewed in FIG. 4. If a 
pivoting of the holder 7 takes place, the extension 77 is likely to roll 
rather than slide along the adjacent portion of the external surface of 
the cushion 5. This also reduces the likelihood of the generation of 
stresses which would tend to expand the cushion. 
The cushion 5 can be used with equal advantage in a screen printing machine 
wherein the holder for the squeegee is reciprocable (rather than 
pivotable) with respect to the support means. Thus, the pintle 6 can be 
replaced by vertical ways for the portion 72 of the holder 7 so that the 
latter can move substantially radially of the stencil 1 (toward or away 
from the pipe 3), depending on the nature of changes in pressure of the 
gaseous fluid which is confined in the cushion 5, as shown by way of 
example in the self-explanatory FIG. 8. All that counts is to employ a 
deformable but non-elastic cushion which effects movements of the holder 
and squeegee toward or away from the internal surface of the stencil 
substantially or exactly opposite the locus where the external surface of 
the stencil contacts the web, and to preferably employ a holder which is 
pivotable or reciprocable and comprises an extension which bears against 
the adjacent portion of the cushion. As mentioned above, it is desirable 
to place the cushion into a recess or socket of the carrier 4 (see the 
U-shaped portion 42) to thus insure that the respective portion of the 
cushion cannot slide relative to the carrier. 
The cushion 5 may comprise a deformable elastic hose which contains one or 
more layers 51 of reinforcing material (see FIG. 3a). The layer or layers 
51 may consist of a textile material, of metallic (e.g., steel) threads or 
wires, or any other material which is not elastic (i.e., which does not 
expand or contract in response to changes in the pressure of fluid in the 
interior of the cushion). If the hose of the cushion 5 is deformable but 
non-stretchable, the reinforcing layer or layers 51 may consist of an 
elastomeric material. The reinforcing layer or layers 51 in the hose of 
the cushion 5 contribute to longer useful life and allow for a more 
accurate regulation of the pressure with which the squeegee bears against 
the stencil. Also, the extent of deformation of the cushion by the 
extension 77 is reproducible with a high degree of accuracy which could 
not be achieved if the wall of the cushion were free to expand or contract 
in response to changes in the pressure of entrapped gaseous fluid. As 
mentioned above, such changes in the pressure of fluid will cause a 
corresponding change in the extent to which the extension 77 penetrates 
into the portion 42 of the carrier 4. 
It has been found that a cushion of the just described type can properly 
bias a squeegee in a screen printing machine wherein the width of the 
material to be printed or otherwise treated by contact with the stencil is 
in the range of up to and even in excess of 5 meters. 
It is also possible to employ a cushion which, when not deformed, need not 
have the shape of a hose with a circular cross-sectional profile as shown 
in FIG. 3a. For example, the portion 42 of the carrier may have an oval 
or even ploygonal outline so that the cushion assumes a complementary 
shape when it is inserted into the carrier and receives compressed gaseous 
fluid while being simultaneously engaged by the extension of the holder. 
It is desirable, however, to employ a cushion which may consist in part of 
elastomeric material but also includes one or more layers of non-elastic 
material (or vice versa) to thus permit a deformation but to prevent 
expansion or contraction of the cushion in actual use. 
If the attendants desire to clean the squeegee 8, the lower end portions of 
the springs 75 are detached from the respective eyelets 74, the pipe 3 is 
moved upwardly together with the support 4 (arrow A in FIG. 4) to raise 
the pintle 6, and the holder 7 is pivoted clockwise (arrow B in FIG. 4) so 
that the edge portion 8A of the squeegee faces upwardly and the entire 
squeegee (save for the head 80) is readily accessible. 
If the squeegee 8 is to be replaced with a fresh or differently 
configurated squeegee, the fasteners 73 are loosened or removed so that 
the portion 72 of the holder 7 becomes separated from the portion 71, and 
the parts 72, 8 are then withdrawn through the one or the other end of the 
stencil 1. It is also possible to remove the squeegee 8 by simply pushing 
it lengthwise of the portion 72 while the latter remains attached to the 
portion 71, and to thereupon introduce the head 80 of a fresh squeegee 
into the socket 76 in a similar way. 
If the machine comprises two or more stencils, each stencil, a single 
stencil, or selected stencils may receive a squeegee which is mounted in a 
manner as shown for the squeegee 8 or 8a of FIGS. 1-4 of FIG. 4a. 
An important advantage of a pintle which is located ahead of the locus 
where the squeegee engages the internal surface of the stencil, as 
considered in the direction of movement of the stencil, is that the 
bearings (brackets 41) for the pintle can take up substantial stresses and 
that such stresses can be distributed along the full length of the 
stencil, depending on the number and distribution of the brackets 41. 
Consequently, and due to the provision of biasing means 75, the force with 
which the squeegee is urged against the internal surface of the stencil 
can be reduced to a minimum so that the machine can employ squeegees which 
consist of thin steel sheet stock, of an elastomeric (rubber-like) 
material, and/or a combination of both. The biasing means 75 which 
counteracts the weight of the holder 7 or 7a and squeegee 8 or 8a insures 
that the friction between the internal surface of the stencil and the 
squeegee can be reduced to a very low value so that the locus of contact 
between the stencil and the squeegee changes very little or not at all and 
that the vibration of squeegee is negligible. The bias of the springs 75 
can be selected with a view to counteract only the combined weight of the 
squeegee and holder 7 and 7a; thus, when the pressure of fluid in the 
cushion 5 is reduced, the squeegee can be lifted off or maintained in 
negligible frictional engagement with the stencil. 
FIG. 2 further shows a compressor K which can supply to the cushion 5 
compressed air through a conduit L. The pressure of fluid in the cushion 5 
can be regulated by a control system R including a throttle valve, a 
shutoff valve and/or others, and one or more gauges. 
FIG. 1 shows two pumps P, driven by motors F, which supply liquid to the 
respective ends of the pipe 3 by way of conduits S. 
The end portions of the pipe 3 extend beyond the bearings or heads 10 for 
the stencil 1 and are mounted in bearing members 91 one of which is shown 
in FIGS. 5 and 6. Each bearing member 91 has a lower portion or jaw 91a 
and an upper portion or jaw 91b which is pivotable at 91c. A threaded 
locking member 96 can be used to hold the portion 91b against pivotal 
movement on the pin 91c. The lower portion 91a is provided with a tapped 
through bore receiving a portion of a feed screw 94 having a handgrip 
portion 95. By rotating the feed screw 94, an attendant can move the 
bearing member 91 transversely of the stencil 1 in ways 92a provided in a 
base 92. The base 92 is movable up and down with respect to an arm 90 of 
the machine frame 9 by rotating a vertical screw 93 which meshes with the 
arm 90 and extends into a socket of the base 92 below the bearing member 
91. The reference characters 97 denote guide pins which are secured to the 
base 92 and extend into vertical holes of the arm 90. The screw 93 allows 
for an accurate adjustment of the level of the corresponding end portion 
of the pipe 3, carrier 4, holder 7 and squeegee 8. 
FIG. 7 illustrates the construction of drive means for rotating the stencil 
1. The illustrated end portion of the stencil 1 is connected with an 
annular holder 1a which is rotatable in the respective head 10 and carries 
a gear 200 forming part of a gear train which further includes the gears 
201, 202, 203, 204 and 205. The gear 205 is mounted on the output shaft 
206 of a prime mover 207, e.g., a hydraulically operated motor. A similar 
train of gears can be provided to drive the other end of the stencil 1. 
The hand wheel 208 of FIG. 7 can be turned to move the hub on which gears 
203, 204 are mounted, in axial direction so as to shift the gear 203 into 
and out of mesh with the gear 202 or the gear 204 into or out of mesh with 
the gear 205. A shield 209 is provided to confine the gear train so as to 
reduce the likelihood of injury to attendants. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can by applying current knowledge, 
readily adapt it for various applications without omitting features which 
fairly constitute essential characteristics of the generic and specific 
aspects of my contribution to the art and, therefore, such adaptations 
should and are intended to be comprehended within the meaning and range of 
equivalence of the claims.