U.S. patent number 3,675,571 [Application Number 05/051,042] was granted by the patent office on 1972-07-11 for screen printing machine for printing in multicolor a horizontally advanced web.
This patent grant is currently assigned to Stork Amsterdam N.V.. Invention is credited to Jacobus G. Vertegaal.
United States Patent |
3,675,571 |
Vertegaal |
July 11, 1972 |
SCREEN PRINTING MACHINE FOR PRINTING IN MULTICOLOR A HORIZONTALLY
ADVANCED WEB
Abstract
A screen printing machine for multi-color printing on a web
which is advanced horizontally on a supporting blanket includes
parallel frame halves across which are mounted bridges. Each bridge
has stencil holders for journaling the ends of cylindrical
thin-walled screen stencils with there being one bridge for each
stencil and the bridges extending parallel to the respective
stencils. At least one end of a stencil is provided with a gear
which meshes with a driving gear mounted in the frame half and
protruding upwardly therefrom. The bridge is mounted on a frame
half by means of a structure which permits adjustment of the bridge
vertically longitudinally and transversely thereof so as to
position accurately the stencil with respect to the advancing
web.
Inventors: |
Vertegaal; Jacobus G. (Boxmeer,
NL) |
Assignee: |
Stork Amsterdam N.V.
(Amstelveen, NL)
|
Family
ID: |
19807427 |
Appl.
No.: |
05/051,042 |
Filed: |
June 30, 1970 |
Foreign Application Priority Data
Current U.S.
Class: |
101/115; 101/116;
101/248 |
Current CPC
Class: |
B41F
15/38 (20130101) |
Current International
Class: |
B41F
15/34 (20060101); B41F 15/38 (20060101); B41f
015/04 () |
Field of
Search: |
;101/115,116,127,127.1,128,128.1,216,248,252 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Eickholt; Eugene H.
Claims
What is claimed is:
1. In a screen printing machine for multi-color printing on a web
advanced horizontally on a support blanket, the combination of a
machine frame having a pair of spaced parallel frame halves, a
bridge mounted across said frame halves, stencil holder means on
said bridge for supporting the ends of a thin-walled screen stencil
so that the screen stencil is parallel to the bridge, a first gear
in one of said frame halves drivingly engaging a second gear on one
end of said stencil, means for mounting said bridge on said frame
halves for longitudinal movement to adjust said stencil
transversely of said web, means on one end of said bridge for
moving said bridge perpendicularly with respect to the longitudinal
direction of the bridge in a horizontal plane whereby the bridge is
inclined with respect to the web, means connecting one end of said
bridge and said first gear for moving said first gear in a vertical
plane parallel to the direction of web advancement only in response
to moving of said bridge one end in a horizontal plane and being
non-responsive to movement of the bridge vertically and
longitudinally, said gears having teeth thereon parallel to the
rotary axes of the gears whereby said gear teeth are slidingly
engageable with each other.
2. In a screen printing machine as claimed in claim 1 wherein said
adjusting means comprises fork members on the ends of said bridge,
and means on said machine frame comprising eccentric means
engageable with said fork members for the vertical adjustment and a
threaded spindle engageable with said fork members for the
horizontal adjustment.
3. In a screen printing machine as claimed in claim 2 wherein said
fork members comprise a first vertical fork member, said actuating
means comprises an internally threaded sleeve horizontally
positioned within said fork member, collar means on the end of said
sleeve on both sides of said first fork member, a threaded spindle
shaft rotatably and non-slideably mounted in a frame half engaging
said sleeve, said spindle shaft extending longitudinally of said
bridge whereby horizontal displacement of the sleeve resulting from
rotation of the spindle shaft is transmitted to said first fork
member.
4. In a screen printing machine as claimed in claim 2 wherein said
fork members comprise a second vertical fork member at one end of
said bridge, said actuating means comprising a shaft rotatably and
non-slideably mounted in a frame half and having an eccentric
thereon closely received within said second fork member, said shaft
being longitudinally of said bridge whereby said eccentric is
freely moveable vertically within said second fork member so that
every horizontal component of movement of said eccentric is
transmitted to said second fork member.
5. In a screen printing machine as claimed in claim 2 and
comprising a horizontally positioned U-shaped member at each end of
said bridge, a pair of shafts rotatably mounted in said frame
halves transversely of said bridge and having eccentric portions
thereon closely received within said U-shaped members respectively,
said eccentric portions slideable freely in said U-shaped members
longitudinally of said bridge whereby vertical components of the
movement of the eccentric portions are transmitted to the
respective U-shaped members.
6. In a screen printing machine as claimed in claim 5 wherein said
U-shaped members are slideable along the respective eccentric
portions in directions transverse to the web, said shafts being
mounted in said frame halves for slideable movement in the
longitudinal and transverse directions of the web.
7. In a screen printing machine as claimed in claim 5 and
comprising a pair of brackets fixedly mounted on the bottoms
thereof on the respective frame halves and supporting the ends of
said bridge thereon, each bracket having a pair of vertical walls
parallel to said bridge and an interconnecting end wall
perpendicular to the bridge, there being horizontal slots in said
vertical walls, said shafts being positioned in said slots
respectively so as to be slideable in directions transverse to the
bridge and web, and a threaded spindle shaft rotatably and
non-slideably mounted in the end wall of one bracket and a shaft
having an eccentric thereon rotatably and non-slideably mounted in
the end wall of the other bracket.
8. In a screen printing machine as claimed in claim 1 wherein said
gear moving means comprises a shaft mounted on said bridge parallel
thereto, a rod having a fork on its upper end and receiving said
shaft, a second shaft slideably mounted in one frame half for
movement parallel to the direction of web advancement and
perpendicular to said rod, the lower end of said rod fixedly
secured to said second shaft, a bearing housing adjacent said first
gear in a frame half and mounted on the driving shaft of the
respective first gear, said slideable second shaft having a
flattened portion connected to said bearing housing.
9. In a screen printing machine as claimed in claim 8 wherein each
frame half has a first gear and said stencil has second gears on
the ends thereof, the first gears in said frame halves protrude
upwardly to engage the second gears on the stencil, a hood
journaled on each bearing housing and pivotable in a vertical plane
parallel to the first gear to expose the first gear to permit
meshing thereof with a said second gear on a said stencil, a fork
on each hood extending around the respective first gear, braking
blocks on said fork engageable with the faces of the first gear,
and a nose on said hood to define a handle for moving the hood,
said hood closing over the first gear when the nose thereof is
released and being moveable with the bearing housing.
Description
The present invention relates to a screen printing machine for
multi-color printing on a web which is horizontally advanced on a
supporting blanket, more particularly, to the adjusting structure
for mounting a cylindrical thin-walled screen stencil on the
printing machine.
Screen printing machines to which the present invention is directed
have been known wherein the stencils can be displaced transversely
with respect to the web which is to be printed. Within limits, such
a adjustment positions the stencil pattern correctly with respect
to the edges of the web. However, a disadvantage of this and
similar screen printing machines is that mutual adjustment of the
stencils and the adjustment of the stencils with respect to the
supporting and driving rollers for the supporting blanket are very
critical.
These screen printing machines have the further disadvantage that
the stencils cannot be adjusted with respect to height in order to
take into account the thickness of the web being printed.
It sometimes occurs that the two end rollers of the supporting
blanket are not exactly parallel with respect to each other and
accordingly the speed of the supporting blanket is not uniform
along its entire width. When the stencils themselves are not
exactly parallel to each other the various colors comprising the
printed pattern are displaced with respect to each other which is
undesirable.
Another maladjustment occurs when a stencil is not exactly parallel
with respect to the structure supporting the supporting blanket.
This will result in a printed pattern which is not equally sharp
and uniform along the width of the printed web.
It is, therefore, the principal object of the present invention to
provide a screen printing machine having novel and improved
adjusting structure therein.
It is another object of the present invention to provide a screen
printing machine wherein the bridge upon which a stencil is mounted
can be adjusted longitudinally, vertically or transversely so as to
be inclined with respect to the web.
It is a further object of the present invention to provide a screen
printing machine wherein the driving gear in the frame for driving
the stencil is moveable together with the adjusting movement of the
bridge, when the bridge is being moved transversely so as to be
inclined to the web.
The screen printing machine according to the present invention
incorporates adjusting structure which permits a universal
adjustability of the stencils with respect to the supporting
blanket and the web. This screen printing machine is also disclosed
in the Netherlands patent applications BvE 69092, BvE 69452 and BvE
69415 applied for by the assignee of the present application.
The screen printing machine is of the type for multi-colored
printing on a web which is advanced horizontally on a supporting
blanket and includes a machine frame comprising a pair of spaced
parallel frame halves. One or more bridges are mounted across the
frame halves and each bridge has mounted thereon stencil holder
means for supporting the ends of a thin-walled screen stencil so
that each screen stencil is parallel to the bridge from which it is
supported. A driving gear for each stencil is mounted in a frame
half and protrudes above the upper surface of the frame half to
engage a second gear on one end of the stencil. A single drive gear
in one frame half or a pair of drive gears in both frame halves may
be provided for each stencil. Hoods may be provided to cover the
drive gears in the frame halves with the hoods being rotatably
mounted on the bearing housings of the gears. The hoods are thus
pivotable in a vertical plane parallel to the gear wheels and can
be swung away to permit engagement of the drive gear with a stencil
gear. The hoods may also be provided with a fork fitting around the
gear with braking blocks being mounted on the fork to engage the
faces of the gear. The hood is provided with a nose to facilitate
opening of the hood and is so arranged that when the nose is not
retained the hood will close over its gear.
Means are provided on one end of the bridge for moving the bridge
perpendicularly with respect to the longitudinal direction of the
bridge in a horizontal plane so that the bridge is inclined or
obliquely positioned with respect to the web. This oblique
positioning of the bridge and its accompanying stencil is important
when the two end rollers of the supporting blanket are not exactly
parallel and, as a result, the linear speed of the blanket is not
uniform along its entire width. This oblique positioning of the
stencil thus compensates for the difference of the linear speed of
the blanket along its width since the end rollers of the supporting
blanket and the stencil are now positioned so that their
longitudinal axis all intersect at a common point which is
obviously at a great lateral distance from the printing
machine.
Means are also provided to connect the end of the bridge and its
respective driving gear for moving the gear in a vertical plane
parallel to the web only when the bridge is being obliquely
positioned. The connection between the bridge and the drive gear
may comprise a vertical rod whose upper end is provided with a fork
fitting around a shaft mounted on the bridge and parallel thereto.
Thus, the rod will move only on oblique positioning of the bridge.
The lower end of the rod is fixed to a sliding shaft at right
angles thereto with the sliding shaft being carried in two brackets
which are fixedly mounted on a frame half so that the sliding shaft
is moveable in a direction parallel to the web. Sliding shaft is
provided with a flattened portion which is attached to the bearing
housing of the drive gear.
Means are also provided for mounting the bridge on the frame halves
for longitudinal movement so as to adjust the stencil transversely
of the web.
Other objects and advantages of the present invention will be
apparent upon reference to the accompanying description when taken
in conjunction with the following drawings, which are exemplary,
wherein;
FIG. 1 is a perspective view of a portion of the screen printing
machine incorporating the present invention;
FIG. 2 is a perspective view of one end of the structure
illustrated in FIG. 1 but viewed from the other side;
FIG. 3 is a longitudinal sectional view of the bridge and adjusting
structure of FIGS. 1 and 2;
FIG. 4 is a sectional view taken along the line IV--IV of FIG.
3;
FIG. 5 is a sectional view taken along the line V--V of FIG. 3;
FIG. 6 is an elevational view of the structure connecting the
bridge and the respective drive gear for moving the gear in
response to oblique positioning of the bridge;
FIG. 7 is a sectional view taken along the line VII--VII of FIG. 6;
and
FIG. 8 is a sectional view taken along the line VIII--VIII of FIG.
6.
Proceeding next to the drawings wherein like reference symbols
indicate the same parts throughout the various views a specific
embodiment of the present invention will be described in
detail.
As may be seen in FIG. 1, each screen stencil 1 is hung on a bridge
2 positioned over a web 3 which is to be printed and is advanced
horizontally in the direction of the arrow 4. The stencil 1 is
supported by end rings 5 in stencil holders 6 mounted on the bridge
2. In the present embodiment of the invention the bridge comprises
a hollow member having end covers 7 to which are secured
projections 8 coupled to brackets 9 whose bottoms are fixedly
secured onto frame halves 10 and 11 of the machine.
As may be seen in FIG. 1 an adjusting knob 12 is provided for
moving the bridge 2 transversely with respect to the web 3.
Adjusting levers 28 and 29 move the bridge vertically to adjust for
height. An adjusting lever 14 mounted in one of the brackets 9
provides for oblique positioning of the bridge 2 with respect to
the stencil. A projection 15 mounted on the bridge is connected to
a vertical rod 16 which in turn is connected with a drive gear
mounted in the frame half 11 in a manner to be later described.
The right hand end of the stencil 1 shown in FIG. 1 is illustrated
in larger scale in FIG. 2 but is viewed from the opposite direction
from that of FIG. 1. It is apparent from FIG. 2 that as the web 3
moves in the direction of the arrow 17, the stencil 1 will rotate
in the direction of the arrow 18 and drive gear 19 will rotate in
the direction of the arrow 20. The drive gear 19 meshes with a gear
(not shown in the drawings) mounted on the end ring 5 of the
stencil and supported in the stencil holder 6. Each drive gear 19
is covered by a protective hood 21 having a nose 22 which when
moved in the direction of the arrow 23 will expose the drive gear
so that the drive gear can drivingly engage the gear on the end
ring 5 of the stencil. As may also be seen in FIG. 2 a nose 22' of
a protective hood is retained in the open position by the stencil
holder 6. The hood 21 is so mounted with respect to the drive gear
19 that when the nose 22 is not retained and is released the hood
21 will automatically close over its drive gear.
Proceeding next to the adjusting means shown in FIGS. 3, 4 and 5,
the mechanism for adjusting the bridge in a direction transverse to
the web is illustrated in the left hand portion of FIG. 3. The
bracket 9 is provided with an end wall 23 in which the unthreaded
portion 24 of a shaft is rotatably and non-slideably mounted. The
adjusting knob 12 is on the outer end of the shaft 24. The inner
end of the shaft is provided with external threads 25 which are
engaged with an internally threaded sleeve 26. The sleeve 26 has
collars on both ends thereof so as to be positioned on both sides
of a vertical fork member 27 extending downwardly from the
projection 8 of the end cover 7. The fork 27 is shown in FIG. 4 and
is freely slideable in a vertical direction along the sleeve 26.
Upon actuation of the adjusting knob 12, the sleeve 26 will shift
since it is threaded upon the threaded end 25 of the shaft and the
collars on the sleeve 26 will act upon the fork 27 so that the
bridge 2 is moved in its longitudinal direction.
Illustrated in FIGS. 4 and 5 are the two adjusting levers 28 and 29
for the mechanism for adjusting the height of the bridge 2. The two
levers 28 and 29 are fixedly mounted upon two eccentric shafts 30
and 31 respectively. On the central portions of the shafts 30 and
31 are eccentrics 32 and 33 respectively. The ends of the shafts 30
and 31 are positioned in horizontal slots 34 and 35 respectively in
the vertical side walls 36 of the brackets 9 and are slideable
therein in a horizontal direction. The vertical walls 36 extend in
the longitudinal direction of the bridge 2. The eccentric portions
32 and 33 of the shafts are received in horizontally positioned
U-shaped members 37 and 38 respectively from the projections 8 and
are slideable therein in a horizontal direction. With this
arrangement it is apparent that turning the adjusting levers 28 and
29 will move the bridge 2 in a vertical direction so that a bridge
can be adjusted for height.
The lever 28 is shown in a position in which the bridge 2 is in the
lower position and the lever 29 is shown in the position with the
bridge 2 being in the higher position. Since the eccentric portions
32 and 33 are horizontally slideable in the U-shaped members 37 and
38 respectively, the shafts 30 and 31, which are for the height
adjustment for the bridge 2, do not interfere with the longitudinal
adjustment of the bridge resulting from actuation of the knob 12.
Operating of the levers 28 and 29 transmits only vertical
components of movement to the bridge.
The mechanism for inclining or obliquely positioning the bridge is
shown in the right hand portion of FIG. 3. Analogous to the left
hand portion of FIG. 3, the end cover 7 has a second vertical fork
member 39 depending therefrom as shown In Fig. 5. The fork member
39 is vertically slideable about an eccentric portion 40 of a shaft
41. Since the lever 14 is fixedly mounted on the shaft 41 rotation
of this lever will transmit horizontal components of motion of the
eccentric 40 to the fork member 39 so that this end of the bridge 2
is moved in a longitudinal direction with respect to the web 3.
Height adjustment of the bridge 2 is not affected by the eccentric
portion of the shaft 41 since the fork member 39 can slide freely
in a vertical direction on the eccentric. When the bridge 2 has
been obliquely positioned or inclined, the shafts 30 and 31 will
move to an inclined position in the slots 34 and 35. The
horizontally disposed U-shaped members 37 and 38 are closed at
their ends so that they carry along the shafts 30 and 31
respectively when the bridge is adjusted in its longitudinal
direction.
In the right hand portion of FIG. 3 and in FIG. 5 there is shown a
portion of the connection between the bridge 2 and the gear wheel
19 with this connection being shown in greater detail in FIG. 6.
The connection is located in the vicinity of one end of the bridge
2 and comprises a vertical rod 16 having on its upper end a fork 42
which fits around a shaft 43 mounted on the bridge 2 and parallel
thereto. The rod 16 thus moves only on an oblique positioning of
the bridge 2 because the fork 42 can slide vertically along the
shaft 43 and slides also along the shaft in a direction parallel to
the bridge 2. The lower end of the rod 16 is fixedly attached at 44
to a shaft 45 to be at a right angle therewith with the shaft being
slideably mounted in spaced brackets 46 and 47 which are fixedly
mounted on the frame half. The shaft 45 has a circular
cross-section throughout most of its length except for a flattened
portion 48 which is connected by bolts 51 and 52 with a bearing
housing 49 which is rotatably mounted on the end of driving shaft
50 of the gear 19 in frame half 11. It is apparent that upon
movement of this end of the bridge 2 in a horizontal plane so as to
obliquely position the bridge, the shaft 45 will slide in its
brackets 46 and 47 to displace the gear 19. The drive gears 19 and
gears on the end of the stencils are provided with gear teeth which
are parallel to their axes of rotation so that meshing gears are
slideable with respect to each other while remaining in driving
engagement.
The drive shaft 50 might be constructed of several components or a
bending load can be applied to it. Self adjusting bearings for this
shaft may also be employed.
As may be seen in FIGS. 6, 7 and 8, the protective hood 21 for the
drive gear 19 is rotatably mounted on the bearing housing 49 for
the shaft of this drive gear. The hood 21 is provided with a fork
53 which fits around the drive gear 19. Braking blocks 54 are
mounted on the fork and engage the faces of the drive gear. Upon
any inclination or oblique positioning of the bridge 2 the hood 21
for the drive gear 19 will move in conjunction with this drive gear
as a result of the structure wherein the hood 21 fits closely
around the bearing housing 49. An important advantage of the
protective hood feature of the present invention is that the hoods
protect at all times operating personnel from the protruding drive
gears in the frame halves.
In the frame half 10 in which the non-sliding drive gears are
journaled, a hood 21 can be rotatably mounted around the bearing
housing for the other end of the shaft 50 whose one end is shown in
FIG. 7. The shaft 50 may on its other end be provided with a drive
gear which engages a gear at the other end of the stencil.
The limits of adjustment of the bridge 2 depend on the space
available for the projections 8 in the brackets 9. In practice, the
adjustment of the bridge can be limited to less than 10 mm which is
quite minute as compared to the length of the bridge which, in
practice, may be more than 1 meter. The angular displacements of
the bridge 2 and the drive shaft 50 are therefore very small so
that the driving engagement of the gears is not affected and no
torsion is produced in the stencils.
The adjustment of the stencils may be based upon reference to
printers proofs made before commencing an actual run of the
printing machine. Upon examination of these proofs, the stencil may
be adjusted in any one of the several different ways described
above. It is thus apparent that screen printing machine of the
present invention is provided with a universal adjustability of the
stencil.
It is understood that this invention is susceptible to modification
in order to adapt it to different usages and conditions and,
accordingly, it is desired to comprehend such modifications within
the invention as may fall within the scope of the appended
claims.
* * * * *