Multicolor rotogravure printing system

A multicolor rotogravure printing system comprising a train of as many monochromatic printing units as the number of the colors required, each printing unit comprising an upper structure including an impression roll and a lower structure including a plate cylinder. These upper and lower structures are adapted to connect and disconnect from each other, and the upper structures are fixed to and suspended from a main frame. Each lower structure has a moving means, thus making it easy to change a used lower structure for a fresh one, and at the same time to perform necessary adjustment of those parts of the printing unit which are made accessible by removal of the lower structure. Also, the length of idle time in printing operation is appreciably reduced.

BACKGROUND OF THE INVENTION 
This invention relates to a multicolor gravure rotary press comprising a 
train of monochromatic printing units each allotted for performing a 
different color printing on an elongated sheet. More specifically, this 
invention relates to a multicolor gravure rotary press comprising a train 
of monochromatic printing units each consisting of an upper structure 
including an impression roll and a lower structure including a plate 
cylinder and an ink device, each said upper structure being integrally 
connected to and suspended from a main frame the end legs of which at the 
opposite extremes with respect to the sheet-feeding direction are fixed to 
the floor of the shop, and each said lower structure when raised, being 
brought into fast union with the associated upper structure. 
The most commonly used conventional multicolor gravure rotary press 
consists of a train of individual printing units each allotted for 
performing a different color printing, thereby finally causing 
multicolored patterns to appear on a sheet in the form of multicolor 
combinations. These individual printing units are separate from each other 
and each is fixed to the floor of the shop. 
With a view to facilitating the work of changing printing plates, the 
entire plate cylinder bearing the printing plate is ordinarily detached 
from the body of printing unit, and then another plate cylinder prepared 
in advance is inserted into the printing unit. Thus, the time required for 
completion of the printing work is accordingly shortened. 
In moving and changing the plate cylinder a carrier is ordinarily used 
because of the relatively heavy weight of the plate cylinder. 
Sometimes a carrier is integrally connected with the body of the plate 
cylinder. In a still better arrangement, the plate cylinder, the ink 
device and other auxiliary parts are built into the carrier. These 
arrangements make it easy to replace the printing plate, and at the same 
time advantageously give the operator plenty of time to clean the printing 
plate and to adjust the various parts of the plate cylinder after it has 
been detached from the printing unit. The combination of the carrier and 
the printing cylinder makes it easier to remove the plate cylinder than 
the use of a separate carrier. There has, however, been no reliable and 
easy means for bringing the carrier-and-plate cylinder assembly into 
engagement with the main frame to which the impression roll is fixed. One 
attempt in this direction has been the provision of a revolving turret, a 
component which itself is entirely unnecessary for a printing machine. 
This turret is provided on the main frame which supports the impression 
cylinder. A carrier bearing a plate cylinder is placed on the turret, and 
then the turret is rotated to bring the carrier into a position at which 
the printing cylinder is aligned to and in contact with the impression 
roll, thereby making the printing machine ready for operation. This 
arrangement makes it easy to align the plate cylinder-and-carrier assembly 
with the impression roll, but still requires laborious work in attaching 
and detaching the plate cylinder from the printing unit. 
As is readily understood from the above, the cost of the conventional 
multicolor printing machine comprising a train of separate monochromatic 
printing units, will increase with the number of different colors to be 
printed, and also, disadvantageously, the conventional multicolor printing 
machine requires laborious and time-consuming work in changing the 
printing plates. With the conventional printing machine it is practially 
impossible to shorten the amount of idle time or reduce the amount of work 
involved in the printing operation. 
One object of this invention is to provide a rotogravure printing system 
which has a structure so simple as to permit the reduction of installation 
cost and which, at the same time, permits easy replacement of the printing 
cylinder so as to improve the working efficiency of the printing machine. 
Another object of this invention is to provide a rotogravure printing 
system of a structure which makes it possible to replace a used plate 
cylinder with a standby in a very short time and also permits mechanized 
transport of plate cylinders by use of guide tracks on the floor of the 
shop. 
SUMMARY OF THE INVENTION 
To attain the objects mentioned above, a multicolor rotogravure printing 
system according to this invention comprises: a main frame standing on 
legs at its opposite ends; a plurality of upper structures spaced from 
each other fixed to and suspended from the main frame, each upper 
structure having female positioner recesses on its lower major surface; a 
corresponding plurality of lower structures each having a plate cylinder, 
male positioner pins to fit into the female positioner recesses of the 
upper structure when brought into fast union, and a carrier means on its 
lower major surface; and a vertical motion means for raising the lower 
structure when brought into the position in which the male positioner pins 
of the lower structure are alligned with the female positioner recesses of 
the upper structure. According to this invention there are provided a 
train of printing units each having upper and lower structures, the upper 
structures being suspended from the common frame thereby eliminating the 
need for printing unit stands and integrating the component printing units 
into a single and simple structure. Each lower structure is provided with 
a plate cylinder and can be easily detached from the upper structure of 
the component printing unit simply by causing the vertical motion means to 
lower the lower structure. In the lowered state the used printing plate on 
the plate cylinder can be easily changed and various parts of the plate 
cylinder can be easily adjusted. Use of a stand-by lower structure reading 
to take the position of the used one makes it possible to minimize the 
length of time for changing the printing plate, and accordingly improves 
the working efficiency of the printing machine. Also, use of guide tracks 
provided in the floor of the shop to extend under each printing unit makes 
it possible to replace and clean the printing plates in such an effective 
and systematic way that the printing operation can be performed at an 
increased efficiency. Further provision of means for driving movable lower 
structures on the guide tracks and of electronic and computer systems for 
controlling such driving means will permit fully automatic, unmanned 
operation. 
The other objects and characteristic features of the present invention will 
become apparent from the description of the invention to be given in 
detail hereinafter with reference to the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, there is shown one embodiment of a multicolor 
rotogravure press according to this invention. As shown, the printing 
machine comprises a train of component monochromatic printing units 
U.sub.1, U.sub.2 and U.sub.3 each performing a different color printing. 
There are provided as many component printing units as the number of 
colors required in printing, and usually three or more component printing 
units are used. A continuous length of sheet S from a feeder F runs over 
the guide rolls and between the impression rolls 5 and the plate cylinders 
6 of the component printing units. After passing between the impression 
roll and plate cylinder of one component printing unit and after being 
printed in the color allotted to that component unit, the sheet runs 
through a drier 16 before reaching the subsequent printing unit. After 
passing through all the component printing units one after another, and 
after being multicolor printed, the sheet is rolled on a rewinder R. 
As mentioned earlier, the conventional multicolor printing machine 
comprises a train of separate printing units (for instance, four component 
printing units for four color printing) each having a stand to support the 
whole body of the component unit on the floor of the shop. In one aspect 
of a multicolor printing system according to this invention, each 
component printing unit comprises a stationary part (upper structure 3) 
and a movable part (lower structure 4), and the stationary part is fixed 
to and suspended from a common frame whose opposite end legs 2 are fixed 
to the floor of the shop, thus integrating all the component printing 
units in a sturdy and simple structure. FIG. 3 shows a component printing 
unit. As shown, the upper structure 3 consists of an impression roll 5, a 
drier 16 and other parts which require no movement in the replacement of 
the printing plate or adjustment of the machine. The upper structure is 
fixed to and suspended from the common frame 1 whose opposite end legs 2 
are fixed to the floor of the shop. The lower structure 4 consists of a 
plate cylinder 6 with a printing plate thereon, an inking device 7 and 
other parts which requiring regular replacement or adjustment. The lower 
structure consitutes a movable and separable component, thus making it 
easy to replace the printing plate and adjust various parts of the 
component unit. Specifically, a stand-by lower structure is provided in a 
state ready to take the place of the used one, thereby reducing the length 
of idle or rest time in printing work, and at the same time eliminating a 
great part of the laborious work involved in replacing printing plates. 
Wheels 8 are provided on the opposite sides of the lower structure frame 
as a means for allowing the lower structure to readily move. As shown in 
FIG. 5, a universal wheel 18 is advantageously provided to allow the lower 
structure to move in all directions. This extra wheel also makes the lower 
structure stable in movement. 
The printing unit is formed by bringing the lower structure 4 into fast 
union with the upper structure 3. This union of the two structures is 
accomplished by the lower structure 4 being pushed up by vertical motion 
means 10 such as, for example, a hydraulic cylinder which is disposed 
below or on the floor of the shop. To ensure exact registration between 
the two structures thus brought into fast union, the structures are 
provided with complimentary positioner means 9 (FIG. 3) which comprise, 
for example, male positioner pins 9b disposed at two or more positions on 
the upper surface of the framework of the lower structure and as many 
female positioner recesses 9a for receiving the male positioner pins 
disposed at corresponding positions on the lower surface of the framework 
of the upper structure. On the floor surface there are provided position 
indicators 17 whose function is to hold moving means 8 in such a position 
that it will permit the lower structure 4 which becomes horizontally 
movable on the floor surface after detachment from the printing unit to be 
brought to the exact position directly below the upper structure 3 prior 
to reunion of the two structures. To permit required separation of the 
printing unit into the upper and lower structures, the driving shaft 12 
serving to convey a rotational motion required to keep the plate cylinder 
6 in motion incorporates a coupling 13 adapted so that the coupling 13 is 
brought into its meshed condition only when the lower structure 4 pushed 
up by the vertical motion means 10 is brought into perfect engagement with 
the upper structure 3. Through the medium of this meshed engagement, the 
rotational motion caused by the line shaft 14 is conveyed through the 
driving shaft 12 and the gear box 15 to the plate cylinder. 
Owing to the aforementioned construction in which the printing unit is 
formed, the lower structure 4 which is made up of the members involved in 
the printing operation can be separated from the stationary upper 
structure 3 which is made up of the members involved in the paper feeding 
operation. In the rotogravure printing system illustrated as a typical 
example adopting this construction, an inking device 7 made up of an ink 
bar 7a, an ink pump 7b and an ink tank 7c, and a doctor 11 serving to 
remove the applied ink from the printing surface are the component members 
of the lower structure 4 in addition to plate cylinder 6. Separation of 
the lower structure from the printing unit renders the work of inspection, 
repair and adjustment of these component members decisively easier to 
accomplish. 
In the illustrated embodiment, there are provided two sets of vertical 
motion means 10 which impart a vertical motion to the lower structure 4. 
Since they are disposed parallel to the direction of the width of the 
printing unit, there is a possibility that the lower structure while in 
vertical motion will be inclined in the lateral direction. To preclude 
this possibility, a receiver plate 19 of a suitable size is disposed at 
the upper end of the shaft of one of the two sets of the vertical motion 
means. Of course, use of only one set of vertical motion means may 
suffice, depending on the conditions of the printing operation. In this 
case, the receiver plate may be in the shape of a disk and may be applied 
to the gravitational center of the lower structure. 
Further for the purpose of facilitating the horizontal motion of the lower 
structure which has been separated from the printing unit in the present 
embodiment, a pair of moving means 8 are disposed one each on the opposite 
sides of the framework of the lower structure and a caster 18 is disposed 
at one end of the framework. The cooperation of moving means 8 and caster 
18 facilitates the determination of the direction in which the lower 
structure is moved. 
Alternatively, two pairs of moving means such as wheels are disposed, like 
the wheels in an automobile, on the opposite ends of the framework of the 
lower structure 4 and a pair of wheel guide tracks 20 such as, for 
example, rails are laid on the floor surface as illustrated in FIG. 6. The 
combination of the moving means with the guide tracks not merely 
facilitates the positioning of the lower structure relative to the upper 
structure but also permits the printing operation such as is illustrated, 
for example, to be managed both systematically and efficiently. 
The preferred embodiment illustrated in FIG. 7 represents a plant composed 
of two parallel printing systems A and B each consisting of six printing 
units. A printing surface washing area C and a waiting area D for standby 
lower structures can be effectively combined with the printing systems A 
and B through the medium of wheel guide tracks. If the printing process is 
programmed in advance, then the standby lower structures having fresh 
printing plates mounted in position thereon can be prepared ready for 
change with those lower structures in use as soon as one printing 
operation is completed. This ready change of lower structures serves the 
purpose of notably shortening the time required for change of printing 
surfaces. The work of inspection and adjustment of parts in the detached 
lower structures can be carried out without interrupting the operation of 
the entire printing plant. 
In the future there will no doubt be a trend toward automation of all the 
miscellaneous jobs related to printing machine operation. The structure of 
the printing machine according to this invention is well adapted to this 
type of automation. For example, the printing machine can be more fully 
automated by incorporating into the lower-structure a self-driving means 
controllable from a remote location. This, however, will increase the size 
of the lower structure, and accordingly increase the difficulty of 
carrying out the control. As a remedy to this problem, as shown in FIGS. 
8A and 8B, a conveyor means 21 is installed crosswise under each component 
printing unit on or in the floor of the shop, and then any one of the 
lower structures can be automatically separated and shifted out from under 
the associated upper structure by controlling the vertical motion means 10 
and then a driving motor 22 associated with the crosswise conveyor. The 
embodiment shown in FIGS. 8A and 8B uses an endless chain conveyor, but 
this should not be understood as limitative, and any other structure which 
meets the practical requirements can be also used. Also, as shown in FIG. 
8A, the conveyor is extended at opposite sides by a length great enough to 
allow the full length of the lower structure to be displaced from under 
the upper structure. In operation, a stand-by lower structure is stationed 
on one of the opposite extensions. The used lower structure is lowered and 
put on the conveyor, and then it is shifted to the other extension, and at 
the same time the stand-by lower structure is shifted to the proper 
position just under the associated upper structure. By this method, the 
replacement of the lower structure can be readily performed. With this 
arrangement and other necessary installations fully automatic unmanned 
printing work can be realized. In an alternative arrangement, a conveyor 
means can be integrally connected to the lower structure and a length of 
cable can be used in place of the endless chain for pulling and shifting 
the lower structure. 
As is apparent from the above, the multicolor rotogravure printing system 
according to this invention greatly reduces the time and work required for 
changing the used printing plates and for performing necessary 
adjustments. Moreover, the system can be optionally provided with conveyor 
means for removal and insertion of the lower structures so that when 
combined with an electronic computer system for controlling the conveyor 
means and other peripheral equipment, fully automatic, unmanned printing 
operation can be realized.