Information
-
Patent Grant
-
6272985
-
Patent Number
6,272,985
-
Date Filed
Tuesday, September 7, 199924 years ago
-
Date Issued
Tuesday, August 14, 200122 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Montgomery; John W.
- Haynes and Boone, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 101 218
- 101 247
- 101 216
- 101 212
- 101 219
- 101 136
- 101 137
- 101 143
- 101 144
- 101 145
- 101 140
-
International Classifications
-
Abstract
A link mechanism is provided for setting and maintaining a minimum spacial distance between a blanket cylinder and a plate cylinder of a rotary printing press. The link mechanism includes a first link arm that is rotatably mounted on an axle of the blanket cylinder at one of the blanket cylinder. A second link arm rotatably is mounted on an axle of the plate cylinder. The first link arm and the second link arm are pivotably connected to each other for single axis pivoting about a point offset to one side of an imaginary line drawn through centers of the plate cylinder axle and the blanket cylinder axle. An adjustment mechanism is positioned between the first and second link arms on projections offset to the other side of the imaginary line so that the set minimum spacial distance between the plate cylinder axles and the blanket cylinder axle can be adjustably set and maintained throughout impression rotation of the rotary printing press.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to a mechanism for maintaining a proper minimum rolling contact spacing between a plate cylinder and a blanket cylinder, under printing pressure, in a sheet-fed, rotary offset printing press and, particularly, to an adjustable link arm mechanism for adjustably setting and maintaining a desired minimum spacial distance and maximum rolling contact pressure between plate and blanket cylinders of a rotary offset printing press.
BACKGROUND OF THE INVENTION
In a sheet-fed, rotary offset printing press, a plate cylinder is fitted with a thin sheet printing plate having the image to be printed photosensitized thereon. The printing plate is supplied with ink and dampening fluid, such that the ink is attracted and dampening fluid is propelled (hydrophobic) to appropriate parts of the photosensitized cylinder and the ink is repelled and the dampening fluid is attracted and coats (hydrophilic) the other parts. This forms an image. Through rolling contact with the blanket cylinder, the image is transferred to the blanket cylinder. The blanket cylinder rolls against an impression cylinder having a sheet of paper or other material to be printed gripped at a leading edge and wrapped around the surface of the impression cylinder. Through rolling contact under an impression force or rolling pressure, the blanket cylinder transfers the ink image onto the paper.
In a multiple color offset printing press, such as a three or four-color printing press, there is a plate cylinder and a blanket cylinder for applying each color with a dot pattern. Each plate for the plate cylinders is photosensitized (made hydrophobic) for attracting ink to dots positioned for applying a single color, or the appearance of a single color, on the final printing product. Typically, three primary colors are applied in a three-color printing press and black ink applied at a fourth printing head. In order to provide a clear, blended color picture, the registration or the positioning of each set of differently colored dots superimposed on the same sheet paper becomes a critical feature and requires each plate and blanket cylinder to be the same diameter, all sets to be synchronously geared to the impression cylinder and rolling contact pressure against the impression cylinder and a makeready position (relaxed pressure, non-contact). It also requires careful adjustment of rotation axial and skew orientation and appropriate contact pressure between the plate and blanket cylinders, as well as between the blanket cylinder with the impression cylinder at each color station or each color head.
Moreover, the plate cylinder relative to the blanket cylinder and the pair of plate and blanket cylinders relative to the impression cylinders, cannot be maintained at a fixed position but, rather, must be moveable relative to each other between an impression position in order to appropriately mount new plates onto the plate cylinders, new blankets on the blanket cylinders and also, to accommodate the thickness of the plates and, further, to appropriately provide an amount of pressure according to the number or density of color dots required for a given color strength and for a particular printing job.
The plate and blanket cylinder are designed to be of equal diameter and the blanket cylinder is sometimes provided with a corresponding groove across its width. On impression, the plate cylinder and blanket cylinder are brought into rolling contact under pressure and the blanket cylinder is brought into rolling contact under impression pressure against the impression cylinder. Even where the bearings and axles are made with a close tolerances and high strength, the amount of pressure across the entire surface of the plate and blanket cylinder is substantial. The rolling contact pressure is often adjusted in terms of the width or thickness of a “stripe” or line across the surface of the contacting cylinders. During makeready, impression pressure is applied with the press stopped, so that the ink and dampening fluid is completely flattened or squeezed off, and it appears to be absent in an area of a stripe across the surface of the cylinders. A thinner stripe corresponds to lighter pressure and a thicker stripe indicates more pressure. When the plate gap rolls past the blanket cylinder, or rolls into a rotary position adjacent to a corresponding blanket gap in the blanket cylinder, the two cylinders, no longer push against each other and they tend to move toward each other slightly, reducing the pressure on the impression cylinder and causing a light print area or a streak. When the cylinders rotate to the other edge of the gap, the cylinders then must move quickly away from each other as the surface-to-surface rolling contact is reinitiated. This can cause a vibration and also can cause a corresponding bounce or chatter, slurring or skipping due to a reduction in pressure and reinitiation of pressure between the blanket cylinder and the impression cylinder. When this change in rolling contact pressure is great, streaking, skipping, bouncing or chattering can adversely and noticeably affect the quality of the print. Even when the change in impression pressure is small, it can less perceivably affect the accuracy of registration of the sets of image-forming dots so that a lack of clarity and precision of the total image can result. This is sometimes referred to as “slurring.” If one color head does not continuously and properly align with the sets of dots for another color head, the image will not be sharp, the color blend will not be true or the image may be blurred or slurred.
In the past, to correct this and to reduce the movement of the plate cylinder with respect to the blanket cylinder and the corresponding change in impression pressure, some press manufacturers have produced circular plates rigidly affixed at either end of the plate and blanket cylinder. The circular plates are machined with a close tolerance and are accurately mounted concentric with the cylinder surfaces to provide a continuous rolling contact. While this prior system avoids the chattering problem, it creates its own problem in that the amount of pressure between the plate and blanket cylinder cannot be easily adjusted from one printing job to the next or cannot easily accommodate printing plates of even slightly different thickness. An experienced press operator can adjust the contact with this type of direct rolling contact end plates by wrapping the plate cylinder with a thin shim sheet of paper prior to attaching the photosensitized printing plate. This takes a substantial amount of time and it is not usually warranted for short runs. Even in instances where the press operator takes the time to remove the plate and install different thicknesses of shim sheets until the desired pressure between the two plates is obtained, Also, it will be seen when the plate cylinder is packed, the blanket will usually also be packed to keep the cylinders the same size. The blanket cylinder is typically gear-driven from the impression cylinder and the plate cylinder is gear-driven from the blanket cylinder. If their rolling diameters are not identical, then the one-to-one rolling contact intended by the gear drive is not necessarily achieved and slippage or slight sliding and blurring between the surface can result.
The adjustment of the pressure between the plate cylinder and the blanket cylinder is often referred to as adjusting the stripe thickness or width. Under pressure the line of contact or flattened ink between one cylinder surface and the other cylinder surface may be wider or narrower, depending on how much pressure there is between the two cylinders. This is often, then, referred to as “adjusting the stripe.” A stripe in a range of ⅛″ to about ⅜″ might be acceptable, depending upon the press and printing job. An experienced press operator can appropriately adjust the stripe width, depending upon factors such as the density of printing of a particular color, the thickness or viscosity of the ink being used and the amount of dampening fluid applied. The stripe is generously proportional to the contacting force or rolling pressure and should normally be the same from one end of the cylinders to the other end.
It can be important to maintain proper printing and registration to adjust the stripe width, yet it is also desirable to avoid the change in pressure caused when each plate connection channel rolls unopposed past the blanket cylinder.
OBJECTS AND ADVANTAGES OF THE PRESENT INVENTION
Thus, it is an object of the present invention to provide adjustable spacing between the plate cylinder and the blanket cylinder and yet to avoid or to minimize the effect of changing pressure or the movement of the cylinders toward and away from each other when the plate gap, for clamping the plate to the plate cylinder and the blanket gap, for clamping the blanket to the blanket, roll past each other.
Thus, it is a beneficial aspect of the present invention to provide a mechanism to adjust the amount of pressure and also to maintain a constant maximum pressure throughout the rotation of the cylinders through a print cycle.
It is a further object to provide a mechanically reliable and economic mechanism that can adjustably set an even pressure across the plate and blanket cylinder and the to allow adjustment of the pressure equally across the cylinders and to then maintain a constant rolling pressure throughout the printing cycle even where the plate cylinder and blanket cylinder have gaps across the surfaces for accommodating the printing plate fastening mechanism that holds the photosensitized plate in an appropriate position on the plate cylinder and for accommodating the blanket fastening mechanism that holds the image transferring blanket in position on the blanket cylinder, respectively.
SUMMARY OF THE INVENTION
The present invention overcomes the drawbacks of the prior presses without bearer disks formed on either end of the plate and blanket cylinders and further overcomes the lack of adjustability of bearer systems in which precision ground, hardened plates are formed or attached on the ends of each cylinder to maintain a constant distance between the plate and blanket cylinder. The present invention provides adjustable link arm mechanisms, including link arm pairs, one arm journaled to the axles of the plate and blanket cylinders adjacent to both ends of the cylinders. The link arms are connected to each other at a mutual pivot point. The pivot point is at a distance offset from a line drawn between the centers of the plate cylinder axle and the blanket cylinder axle. On the other side of the imaginary line, projections from the two link arms are adjustably moveable toward or away from each other to pivot the link arms and thereby increase or decrease the minimum distance between the two axles. Thus, the maximum rolling force is fixed by setting the minimum distance between the two cylinders. A spring mechanism provides the arms with a capability of pivoting to a larger distance so that the cylinders can be moved away from each other to a “makeready” position for replacing the plate, replacing the blanket or for cleaning the cylinders for the next printing job. Yet, under impression, the distance that the plate cylinder axle and the blanket cylinder axle can move toward one another is stopped by the link arm mechanism at an adjustably fixed distance. The unique link arm mechanism also permits separate adjustment for either end of the cylinders. In one embodiment, once the two ends are adjusted to be at an equal distance, both ends can be adjusted equal amounts simultaneously to increase or decrease the stripe width equally entirely across the cylinders.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing objects, advantages, and features, as well as other objects and advantages, will become more apparent with reference to the description and drawings below, in which like numerals represent like elements and in which:
FIG. 1
is a perspective view of a multiple color, offset rotary printing press, having adjustable link arms positioned between the plate and blanket cylinders according to the present invention;
FIG. 2
is a schematic partial cutaway plan view of a plate cylinder, blanket cylinder and impression cylinder mounted for rotation in a frame of a printing press according one embodiment of the present invention, showing the position of the pairs of adjustable link arms immediately adjacent either end of the plate cylinder and blanket cylinder and positioned inside of the printing press frame;
FIG. 3
is a perspective view of a plate cylinder and blanket cylinder with adjustable link arms positioned therebetween according to one embodiment of the present invention in which duplicate pairs of link arms would be positioned on either side of the plate and blanket cylinders.
FIG. 4
is a depiction of a plate and blanket cylinder having a pair of adjustable link arms positioned on either end and further including an adjusting rod having dual cams thereon for adjusting both ends of the plate and blanket cylinders at the same time;
FIG. 5
is an enlarged partial cutaway top plan view of one pair of adjustable link arms corresponding to the link arms of
FIG. 3
; and
FIG. 6
is an enlarged partial cutaway top plan view of one pair of adjustable link arms with one of the dual cam adjusters depicted according to the embodiment depicted in
FIG. 4
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1
shows a side perspective view of a multiple color rotary offset printing press
10
, including multiple color print heads or printing stations
12
(
a
), (
b
), (
c
) and (
d
). Each of the print heads
12
include a plate cylinder
14
(
a
), (
b
), (
c
) and (
d
), and also a blanket cylinder
16
(
a
), (
b
), (
c
) and (
d
). Under each print head
12
(
a
)-(
d
) also include a set of inking rollers
18
(
a
)-(
d
) and a dampening roller system
20
(
a
)-(
d
).
The plate cylinders and blanket cylinders
14
(
a
)-(
d
) and
16
(
a
)-(
d
), respectively, are mounted to a press frame
22
, having front
24
and back
26
frame members, generally defining parallel planes at which the plate cylinders
14
and blanket cylinders
16
are mounted through plate cylinder axles
28
(
a
)-(
d
) and blanket cylinder axles
30
(
a
)-(
d
), respectively. An impression cylinder
32
is also rotatably mounted to front
24
and back
26
frame members through an impression cylinder axle
34
. The impression cylinder
32
is connected through axle
34
to an impression drive gear
36
. The impression drive gear
36
engages with blanket cylinder gears
38
(
a
)-(
d
), each of which, in turn, engage with plate cylinder gears
40
(
a
)-(
d
), respectively. When the press
10
is operating in the impression mode, each blanket cylinder
16
is moved into rolling control pressure engagement with the impression cylinder
32
. The impression cylinder carries grippers in gaps that hold on its surface the paper sheets to be printed. The plate cylinders
14
are also engaged with rolling contact pressure with blanket cylinders
16
. The impression gear
36
is engaged with the blanket cylinder gears
38
which, in turn, are engaged with plate cylinder gears
40
for direct drive rolling contact between impression cylinder
32
and the blanket cylinders
16
and, in turn, between blanket cylinders
16
and the impression cylinders
14
. Other gears, such as feed gear
42
, may also be appropriately engaged for sheet feeding through sheet feeder
46
so that sheets to be printed can be gripped at printing stations
44
(not shown) circumferentially around impression roller
32
. The sheets to be printed are rotated through and past each printing station
12
(
a
)-(
d
) for adding each color printing and for subsequent removal and collection in sheet collection area
48
.
To facilitate and maintain accurate spacing and registration between each of the plate cylinders
14
and corresponding blanket cylinders
16
, according to the present invention, a first inventive link arm mechanism
50
is connected between plate cylinder axles
28
and blanket cylinder axles
30
between the front frame member
24
and front ends
11
and
13
of plate cylinder s
14
and blanket cylinders
16
, respectively. A second link arm mechanism
52
is also positioned between back frame member
26
and the back ends
15
and
17
of plate cylinders
14
and blanket cylinders
16
, respectively. The link arm mechanisms are adjustable to set the minimum spacing between the plate cylinders
14
and the blanket cylinders
16
. The minimum spacing is maintained throughout an entire impression rotation cycle. The link arm mechanisms
50
and
52
are desirably positioned at opposite ends of the plate cylinder and blanket cylinders at each of the plurality of color printing heads or color printing stations. Each link arm mechanism
50
and
52
is preferably provided with a separate adjustment mechanism
54
and
56
for separately adjusting the spacing between the plate cylinders
14
and blanket cylinders
16
at the front ends
11
and
13
and also for separately adjusting the spacing of the plate
14
and blanket
16
cylinders at the back ends
15
and
17
, respectively.
Also, advantageous in a preferred embodiment, a control rod
58
is attached and traverses across the press
10
from the front end adjustment mechanism
54
of first link arm mechanism
50
to the back end adjustment mechanism
56
of second link arm mechanism
52
. The control rod
58
is constructed for simultaneously changing cylinder-to-cylinder spacing caused by first link arm
50
, as well as the spacing caused by second link arm
52
, in exactly the same amount. This contrasts to the individual adjustment mechanisms
54
and
56
, which allow the spacing at the front ends to be adjusted separately from the spacing at the back-ends link arm
52
.
FIG. 2
is a schematic partial cutaway plan view of a plate cylinder
14
, blanket cylinder
16
and impression cylinder
32
mounted for rotation in a frame
22
, between frame members
24
and
26
, of a printing press
10
, according to one embodiment of the present invention. The position of pairs of adjustable link arms
50
and
52
are immediately adjacent either end of plate cylinder
14
and blanket cylinder
16
, and are positioned inside of the printing press frame. In the embodiment depicted in
FIG. 2
, the blanket cylinder is journaled to a pair of pressure application arms
110
and
112
, so that they may move into and out of impression contact with impression cylinder
32
wherein axle
30
moves relative to frames
24
and
26
in slots
114
and
116
, respectively. Similarly, plate cylinder
14
is attached to frame
24
and
26
through pressure application members
118
and
120
which are moveable within slots
122
and
124
, cut through frame members
24
,
26
and also through blanket cylinder pressure application members
110
and
112
. The slots and pressure arms are only schematically depicted, as different presses use different mechanisms for applying the impression pressure between the blanket cylinder
16
and the impression cylinder
32
, as well as the image transfer pressure between plate cylinder
14
and blanket cylinder
16
.
An important aspect, with respect to the present invention, is that the link arm mechanisms
50
and
52
, including the pairs of pivotably attached link arms, may pivot outwardly away from the adjustable stops
54
and
56
, but are prevented from moving inwardly beyond the minimum adjusted distance
100
between axles
28
and
30
. Also, importantly, the close proximity of the locations between the link arms
50
and
52
and the ends of plate cylinder
14
and blanket cylinder
16
reduces any flexure that may otherwise occur in the connection between the axles
28
and
30
and the frame member
24
and
26
.
FIG. 3
is a partial perspective view of a plate cylinder
14
and a blanket cylinder
16
with adjustable link arms
50
connected between plate cylinder axle
28
and blanket cylinder axle
30
, according to one alternative embodiment of the present invention. The link arm mechanism
50
further comprises a pair of link arms
60
and
64
. A first link arm
60
is rotatably connected to the plate cylinder axle
28
through a first bearing
62
. A second link arm
64
is connected to the blanket cylinder axle
30
through a second bearing
66
. Both link arms are pivotably interconnected at a single axis pivot
68
. The link arms
60
and
64
are constructed so that pivot
68
will be a spaced-apart distance
70
from an imaginary line
72
drawn between centers
74
and
76
of plate cylinder axle
28
and blanket cylinder axle
30
, respectively. When the plate cylinder
14
and blanket cylinder
16
are in the impression rolling contact for printing the offset distance
70
is advantageously more than about 5% of the diameter of the cylinders. Preferably, for 6¾″ diameter cylinders, the offset
70
is more than about ½″, i.e., preferably more than about 7.5% of the diameter of the plate cylinder for the blanket cylinder and less than about 50% of the diameter of the cylinders.
It will be seen in
FIG. 3
that the rolling contact between the plate cylinder
14
and the blanket cylinder
16
is, in fact, rolling contact between the surface
80
of a photosensitized plate
82
secured at a leading edge
84
and also secured at a trailing edge
86
into a plate-securing gap
88
. Surface
80
of plate
82
is in contact with blanket cylinder surface
90
under impression and less than about 50%. The blanket cylinder may be provided with a corresponding blanket-securing gap
92
that is synchronized through the direct gearing (not shown in
FIG. 3
) to correspond during rotation to overlap plate gap
88
. The plate gap
88
and blanket gap
92
present a void and lack of surface
80
to surface
90
rolling contact such that rolling pressure between plate cylinder
14
and blanket cylinder
16
would be unopposed during that segment of rotation. Any play or flexure slack in the bearings, in the pressure application arms or in the mounting mechanism to frames
24
and
26
can produce movement. Any flexing in the axles will be amplified over the distance the cylinders are spaced from the frame members
24
and
26
. Thus, the lack of rolling contact may cause the blanket cylinder and plate cylinder to move toward each other as the gaps
88
and
92
are traversed and away from each other as leading edge
84
reinitiates contact between surface
80
and surface
90
. However, with the link arms
60
and
64
rotatably journaled at
62
and
66
in place on axles
28
and
30
, rigidly pivoted at single axis pivot point
68
, and provided with adjustment device
54
for adjustable spacing of distance
93
, the movement of the cylinders is minimized or avoided. Thus, because there are two points of contact, namely at pivot
68
and at adjustment mechanism
54
, the minimum distance
100
between axles
28
and
30
becomes adjustably fixed. In the embodiment depicted, adjustment mechanism
54
is shown as a bolt
98
threadably engaged through projection
94
and abutting against a surface of projection
96
. Other adjustment mechanisms might be used without departing from certain aspects of the invention provided that the adjustment can be fixed at the desired spacing throughout the impression cycle of the print head.
It will be noted, however, that because the link arms
60
and
64
may pivot, at
68
about a single axis parallel to the cylinder axles, to away from the abutting contact of bolt
98
with projection
96
, the distance between axles
28
and
30
may be increased during makeready without adjusting mechanisms
50
or
54
, so that the photosensitized printing plate
82
may be removed and replaced. The blanket may be replaced in blanket cylinder
16
or the cylinders may be cleaned and the press may be maintained or repaired as needed to make it ready for the next printing job.
In
FIG. 4
, an alternative embodiment of the inventive link arm mechanism is disclosed as a pair of adjustable link arms positioned on either end of plate cylinder
14
and blanket cylinder
16
. In this embodiment, the link arm mechanism
50
is on one end and the link arm mechanism
54
is on the other end of the cylinders. Link arm mechanism
50
includes a first link arm
60
rotatably mounted on axle
28
of plate cylinder
14
and a second link arm
64
rotatably attached through bearing
66
to axle
30
of blanket cylinder
16
. Blanket cylinder
16
is shown in rolling impression contact with impression cylinder
32
and also in rolling contact with the surface of plate cylinder
14
. The adjustment mechanism
54
can be used to establish the minimum distance
100
between the centers of axles
28
and
30
, both on link arm mechanism
50
and the opposite end link arm mechanism
52
. When a consistent stripe width is set at both ends using the independent or separate adjustment mechanisms
50
and
54
, the position may be secured in place, as with a locking nut or a set screw
55
, as shown. For example, when the width of the stripe is consistent across the entire axial length of surfaces
90
and
80
, then both ends may be equally adjustably spaced simultaneously using control rod
58
.
In the embodiment schematically depicted in
FIG. 4
, control rod
58
comprises a rod extending from the front ends to the back ends of cylinders
14
and
16
. Control rod
58
is rotatably engaged in one projection
94
of one of the arms
60
of link arm mechanism
50
and no projection
95
of one of the arms of link arm mechanism
52
. Upon turning control rod
58
, an eccentric
102
and an eccentric
104
, both identically sized and aligned, rotate against separate adjustment mechanisms
54
and
56
so that both ends of the plate cylinder and blanket cylinder are provided with the same minimum spacing distance
100
. The control rod
58
can be locked in place at a set adjustment with a set screw
130
or
131
.
When the press is placed in a makeready condition, the pressure is released between blanket cylinder
16
and impression cylinder
32
. The pressure is also released between blanket cylinder
16
and plate cylinder
14
. The link arm
60
pivots at pivot
68
with respect to link arm
64
so that the increase in distance between the axles
28
and
30
is accommodated. This will occur automatically through the use of a compression spring
106
held in position between projection
94
and
96
of link arm mechanism
50
and a compression spring
108
held in position between projections
95
and
97
of link arm mechanism
52
.
FIG. 5
is a schematic cutaway plan view of the separate adjustment mechanism according to the embodiment depicted in FIG.
3
. The adjustment mechanism
54
comprises a bolt
98
threadably engaged through projection
94
of link arm
60
. The bolt
98
abuts against a surface
126
of projection
96
and is locked in place, as with a set screw
55
, to maintain a fix, after adjustment, minimum separation distance
92
. A compression spring
106
is appropriately positioned and secured between projections
94
and
96
, so that upon makeready, when the blanket cylinder and plate cylinder are separated from one another, the projections
94
and
96
are pushed into separation by compression spring
106
. When the impression pressure is again applied, the compression spring
106
compresses, but it cannot compress beyond the minimum distance
92
, as fixed by adjustment mechanism
54
. The blanket cylinder and plate cylinder will not be able to move toward each other any closer than the minimum distance
100
thus established.
FIG. 6
is a schematic partial cutaway top plan view of projections
96
and
94
of link arm mechanism
50
according to the embodiment depicted in FIG.
4
. The separate adjustment mechanism
54
is a bolt
98
having threadably engaged through projection
94
and having mechanism
50
as a set screw
55
. A portion of the control rod
58
is shown journaled at
128
through a portion of projection
96
. The locking mechanism bolt
98
is adjustably positioned for contact against a cam surface or eccentric
102
so that link arm mechanisms at both ends of the cylinders can be simultaneously adjusted equal amount with the control rod
58
. A lock mechanism
130
may also be provided, such as a set screw
130
, to precisely maintain the minimum separation distance
93
between projections
94
and
96
so that the minimum adjusted distance
100
between axles
28
and
30
will also be maintained. Compression spring
106
is positioned between projections
94
and
96
so that the separation distance between projections
94
and
96
increases when the press is moved into a makeready condition and the spring is compressed when the press is moved into a printing or impression pressure condition.
Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading the present disclosure, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.
Claims
- 1. A link mechanism for maintaining minimum spacial distance between a plate cylinder and a blanket cylinder of a rotary printing press, said link mechanism comprising:a) a first link arm rotatably mounted on an axle of said plate cylinder at one end of said plate cylinder; b) a second link arm rotatably mounted on an axle of said blanket cylinder at a corresponding blanket cylinder; and c) said first link arm and said second link arm forming a pair of link arms pivotably connected to each other for single axis pivoting about a single axis parallel to the plate cylinder and blanket cylinder axles through a point on one side of an imaginary line drawn through centers of said plate cylinder axle and said blanket cylinder axle and having an adjustment mechanism positioned between the link arms on the other side of said imaginary line so that a minimum spacial distance between said plate cylinder axles and said blanket cylinder axle can be adjustably set and maintained throughout an impression rotation of said plate and blanket cylinders.
- 2. The link mechanism of claim 1 further comprising another pair of said first and second link arms on another end of said plate cylinder and said blanket cylinder of said rotary printing press.
- 3. The link mechanism of claim 2 further comprising a separate mechanism for adjustment of the spacing between each of said pairs of link arms so that a desired relative “stripe” thickness indicating consistent rolling contact pressure between said plate and blanket cylinder can be adjustably set at either end across the width of said plate and blanket cylinder.
- 4. The link mechanism of claim 3 further comprising a control rod having dual cams for simultaneously adjusting the spacing of said link arms on both ends of said plate and blanket cylinders.
- 5. The link mechanism of claim 1 wherein said offset distance of said single axis pivot point of said first and second link arms is at a distance from said imaginary line drawn between axle centers greater than about 5% of the diameter of the plate cylinder.
- 6. The link mechanism of claim 1 wherein said single axis pivot point of said first and second link arms is at a distance, from said imaginary line drawn between axle centers, greater than about 7.5% of the diameter of the plate cylinder.
- 7. A multiple color head offset rotary printing press having an impression cylinder and a plurality of plate cylinders and blanket cylinders, one for each color to be printed, said printing press further comprising:a) a first link arm rotatably mounted on an axle at one end of each of said plurality of plate cylinders; b) a second link arm rotatably mounted on an axle at a corresponding one end of each of said blanket cylinders; and c) said first link arm and said second link arm forming a pair of link arms pivotably connected to each other for pivoting about a single axis parallel to the plate cylinder and blanket cylinder axles through a point on one side of an imaginary line drawn through centers of said plate cylinder axle and said blanket cylinder axle and having an adjustment mechanism positioned between the link arms on the other side of said imaginary line so that a minimum spacial distance between said plate cylinder axles and said blanket cylinder axle can be adjustably set and maintained throughout an impression rotation of said plate and blanket cylinders.
- 8. The multiple color head offset rotary printing press of claim 7 further comprising another pair of said first and second link arms on another end of each of said plurality of said plate cylinders and said blanket cylinders of said rotary offset printing press.
- 9. The multiple color head offset rotary printing press of claim 8 further comprising a separate mechanism for adjustment of the spacing for each of said pairs of link arms so that a desired relative “stripe” thickness indicating consistent rolling contact pressure between said plate and blanket cylinders can be adjustably set at either end across the width of said plate and blanket cylinders.
- 10. The multiple color head offset rotary printing press of claim 9 further comprising a control rod having dual cams for simultaneously adjusting the spacing of said link arms on both ends of each of said plurality of said plate and blanket cylinders.
- 11. The multiple color head offset rotary printing press of claim 7 wherein a distance of said single axis pivot point of said first and second link arms from said imaginary line drawn between axle centers is greater than about five percent of the diameter of the plate cylinders.
- 12. The multiple color head offset rotary printing press of claim 7 wherein a distance of said single axis pivot point of said first and second link arms from said imaginary line drawn between axle centers is greater than about 7.5% of the diameter of the plate cylinders.
US Referenced Citations (7)