Printing press coupler accumulator

A sheet accumulator for advancing successive sheets between first and second color printing presses comprising an accumulator sheet conveyor for advancing sheets from one press to the other press, a sheet lifter at the conveyor to lift a first sheet and thereby enable the sheet conveyor to advance a second sheet beneath the first sheet, and a sheet sensor at the conveyor, operably associated with the sheet lifter to actuate and deactuate the sheet lifter based on the position of the sheet.

BACKGROUND OF THE INVENTION 
This invention relates to a sheet accumulator, and to successive printing 
presses combined with an intermediate sheet accumulator to produce printed 
sheets of two or more colors. 
The use of two color printing presses, such as stencil screen presses, in 
sequence to produce two color prints is old. Each press is a functional 
stage of operation. Each press typically has a dryer, e.g., a UV dryer, to 
rapidly dry the printed ink from that press before the next functional 
stage is encountered. To do this, the presses have been known to be put in 
synchronous drive with each other as with a jack shaft. Unfortunately, the 
actual processing of the sheets in the first press might get out of 
synchronism with the processing in the second press for various reasons. 
For example, if the first press runs out of sheet stock, it has to be 
stopped temporarily to be reloaded. To continue to run it would cause ink 
to pass through the stencil screen and be deposited on the equipment. If 
the first press is stopped and the two presses are synchronously 
interlocked, the second press will stop. However, since the second press 
will likely have stock in its dryer, the dryer will quickly overheat the 
sheet stock to potentially cause a fire. If the second press is caused to 
continue running, as to prevent stock overheating, it will soon run out of 
stock from the first press and deposit ink on the equipment. 
Alternatively, if the second press needs to be stopped for some 
operational reason, the continued output of sheet stock from the first 
press will quickly jam up at the discharge end of the first press, causing 
loss of product and other significant problems. If the first press is 
stopped simultaneously with stoppage of the second press, the sheet 
product of the first press will be stalled in the dryer, creating an 
overheating and potential fire problem. Furthermore, if there are three or 
more colors to be applied to each sheet, the potential problems of trying 
to correlate the presses, or the potential costs of operating them 
independently, become even more magnified. 
Consequently, sequential two color sheet printing presses have caused 
significant operational problems for those in the industry. In view of 
these problems, it is normally preferred to run each press and dryer 
independently, even though this requires performing each color printing as 
a separate operation and greatly increases the cost of printing. 
SUMMARY OF THE INVENTION 
The present invention provides a unique sheet accumulator for 
interconnecting successive printing presses, such that the printing 
presses can be simultaneously operated at the same synchronized output 
speed or at differing speeds, or either press can continue to operate 
while the other one is temporarily stopped, yet without the difficulties 
previously encountered. Thus, the first press can be stopped temporarily 
to restock it with sheet stock to be printed, while continuing operation 
of the second press; or the second press can be stopped temporarily while 
the first press continues to function, yet without the output from the 
first press jamming. The presses can be run at the same speed or somewhat 
different speeds, and the presses can also be temporarily run 
independently or stopped, as desired. 
The accumulator has a sheet accumulator conveyor, a sheet stop, a sheet 
lifter which is preferably a suction head, for lifting the tail end of a 
sheet to allow a successive sheet to underlap it in shingle fashion, and a 
sensor such as a photoelectric eye to control actuation and deactuation of 
the lifter. Preferably a prefeed conveyor is employed downstream of the 
first press dryer and upstream of the accumulator conveyor so as to 
quickly remove sheets from the first dryer while the accumulator sheet 
conveyor is operated at a slower speed, to assure optimum underlap 
shingling of the sheets. 
The accumulator is positioned between selected printing presses, 
specifically between a dryer for the first press and the infeed for the 
second press. 
Additional presses can be successively positioned relative to the first and 
second presses to obtain three or more color prints. These successive 
presses and cooperative sheet accumulators can be added in modular fashion 
to produce the desired number of colors for the printed product. 
These and other features, advantages and objects of the present invention 
will be further understood and appreciated by those skilled in the art by 
reference to the following specification, claims and appended drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring now specifically to the drawings, the multiple press printing 
assembly 10 includes a first printing press 12, a first feeder 14 to 
cylinder press 12, a first dryer 16 downstream from press 12, a second 
printing press 22, a second feeder 24 to printing press 22, a second dryer 
26. Between the two press and dryer subassemblies, and specifically 
downstream of the first dryer 16 and upstream of the second feeder 24, is 
the novel shingle accumulator 18. Optionally, downstream of the entire 
assembly is a conventional stacker jogger 30. 
Each of the presses 12 and 22 may be of any conventional type, preferably 
stencil screen printing presses, of the type shown, for example, in U.S. 
Pat. No. 5,372,066 issued Dec. 13, 1994, which is incorporated by 
reference herein. Each press is capable of depositing ink in select 
locations on the sheet stock being advanced sequentially through the 
assembly. The ink is typically deposited by passing a squeegee over a 
stencil screen which allows passage of the ink through the screen only in 
select areas to produce the desired print pattern on the sheet stock. The 
two presses 12 and 22 will normally print different color inks to produce 
the desired effect on the final printed sheet stock. Two presses are shown 
in succession in this illustrative example. It will be understood that 
three or more presses may be used in sequence, depending on the number of 
colors desired to be printed. 
The sheet stock is normally paper, but can be paperboard, plastic, metal, 
or other sheet stock materials to be printed for the desired final end 
use. 
The feeders 14 and 24 are conventional in type, including known means for 
storing a limited quantity of sheet stock and advancing the individual 
sheets seriatim to the presses. 
The dryers 16 and 26 are of conventional type, such as UV dryers which dry 
the ink on the previously printed sheet stock as the printed sheets pass 
through the dryer on a conveyor in conventional fashion. The sheet stock 
normally has a time limit during which it can be retained in the dryer, 
particularly if the sheet stock is combustible. Dryer 26 preferably has a 
cooling zone following the drying zone. Optionally, a drop gate 32 can be 
located downstream of press 12 and upstream of dryer 16 so that, during 
nonoperational time periods, access can be had to the press and dryer 
mechanisms for adjustment, repair, or the like. Similarly, press 22 can 
include a drop gate 42. The drop gate can be pivotally mounted to move 
between the horizontal upright position depicted in FIG. 2 in solid lines, 
and the dropped lowered vertical position depicted in phantom lines in 
FIG. 2. Between the two press subassemblies, and specifically downstream 
of the first dryer 16 and upstream of the second feeder 24, is a shingle 
accumulator 18. Optionally, a drop gate 38 can be downstream of the 
shingle accumulator 18 to move from a horizontal orientation cooperative 
with feeder 24 and a dropped lowered orientation depicted in FIG. 2. 
Referring to FIG. 3, the accumulator assembly 18 is shown to include a 
prefeed conveyor 50 such as one or more belts 52 which are recirculated 
around a pair of spaced parallel rolls 54 driven by belt or chain 56 from 
motor 58. This conveyor receives sheet stock, i.e., substrate from the 
discharge conveyor 16' of first dryer 16. Preferably a tension wheel 60 
positioned on a pivot arm 62 above belt 52 causes sufficient downward 
pressure on the sheet stock or substrate to assure driving engagement by 
belt 52 on the substrate or sheet stock. Downstream of prefeed conveyor 50 
is accumulator conveyor 70 which comprises one or more belts 72 that 
travel around spaced parallel rollers 74 driven by a belt or chain 76 from 
a variable speed sheave 78 driven by belt 80 from motor 58. Sheave 78 
allows the speed of conveyor 70 to be adjusted relative to the speed of 
conveyor 50. This conveyor advances successive sheets to a vertically 
oriented stop 94 which serves as a stock guide for press 22. 
Adjacent the infeed end of conveyor 70 is a stock sensor 86, preferably in 
the form of a photoelectric eye. It is positioned and oriented to detect 
the presence of an advancing sheet fed from conveyor 50 onto conveyor 70. 
Above conveyor 70, intermediate its ends and normally downstream from 
sensor 86, is a sheet lifter, preferably one or more sucker heads 90. 
Sensor 86 actuates sucker heads 90. These sucker heads are vertically 
shiftable so as to be lowered to engage the tail end of a sheet of stock, 
and then raised to elevate this tail end of the sheet to enable the 
successor sheet to pass therebeneath in interleaved or shingle fashion. 
The sheet lifter sucker heads are preferably of the type in U.S. Pat. No. 
4,580,773 incorporated by reference herein. The controlled positioning of 
successive sheets by the accumulator enables the two presses to have 
different modes or speeds of operation. 
At the downstream end of accumulator conveyor 70 is preferably a lifting 
mechanism such as another plurality of the same type of sucker heads 25 to 
engage the leading end of the forwardmost sheet of stock and lift it 
upwardly over the level of the stock guide vertical panel 94 for 
advancement of the sheet by conveyor 70 to shift the leading edge of the 
stock between the conveyor rolls 96 that feed the second press 22. 
In explaining operation of the accumulator, a series of five substrates or 
sheets of stock are shown in FIG. 3 as S1, S2, S3, S4, and S5. Sheet S1 is 
shown with its leading edge having been engaged by sucker heads 25 and 
elevated above the level of the stock guide 94, ready to be advanced into 
the second printer 22. Sheet S2 is shown with its leading edge abutted 
against stock guide 94 and having its tail end above the forward portion 
of subsequent sheet S3 to be interleaved in shingle fashion. Subsequent 
sheet S3 is shown with its forward end interleaved beneath sheet S2 and 
its tail end momentarily elevated by sucker 90 to allow the forward end of 
subsequent sheet S4 to be conveyed beneath the tail end of sheet S3 in 
shingle fashion. Sheet S4 is shown above sensor 86, having been 
transferred from prefeed conveyor 50 to accumulator conveyor 70, and its 
leading edge having actuated sensor 86 which in turn actuated lifter 
suckers 90. Sheet S5 is shown being discharged from the first dryer 
conveyor 16' and engaged by wheel 60 to be advanced by prefeed conveyor 
50. 
During the printing process, and as the sheets which have been printed on 
the first press 12 advance to the accumulator 18, each sheet is 
transferred from the first dryer conveyor 16' to prefeed conveyor 50 and 
hence to accumulator conveyor 70 to be moved toward the stock guide 94. 
Successive sheets are specially accumulated to prevent jam up because, as 
each sheet is transferred from conveyor 50 to conveyor 70, its leading 
edge is detected by sensor 86 which actuates lifter sucker heads 90 to 
release the tail end of the previous sheet. As the tail end of a sheet 
passes sensor 86, the lifter sucker head 90 is actuated to allow the 
sucker head to pick up the tail edge of this sheet. 
Consequently, if the second printing press is temporarily shut down for 
some reason, the output from the first press will not jam up and cause 
damage and will not remain in the first dryer too long to create a 
potential fire hazard. Similarly, if the first press is shut down 
temporarily in order to reload print stock, for example, the second press 
can continue to feed sheets from the accumulator. Both presses may be shut 
down simultaneously if desired, or may be run independently. If the first 
press feeds sheet output at a different rate than the second press, the 
accumulator accommodates the differential. Thus, it may be desired to have 
the first press operate slightly faster than the second press, creating a 
temporary organized backlog at the accumulator, following which the first 
press may be shut down to reload print stock and during which the 
accumulator allows steady infeed to the second press. 
In FIG. 4 is an example circuit diagram for the control system. The shingle 
accumulator control system is shown to contain the following electrical 
components, main drive motor 58 (120 vac), photo eye sensor 86 (120 vac), 
and an air piloted solenoid vacuum valve (120 vac). The accumulator 
operates between the two presses 12 and 22 and is controlled in automatic 
mode by press 22 through relay R22. When relay R22 is energized, power is 
delivered to the DC drive and energizes the main drive motor. The main 
drive motor rotates the conveyor belts on the accumulator that transfer 
the sheet. When the sheet passes over the electric eye 86, relay R2 
energizes, de-energizing the solenoid vacuum valve. The solenoid vacuum 
valve is located between a vacuum generator and the suckers on the sucker 
head 90 and closes to turn off vacuum at the sucker head. After the sheet 
has passed over the electric eye, relay R2 de-energizes, energizing the 
solenoid vacuum valve, causing the sucker head to pick up the tail end of 
the substrate, i.e., sheet. Relay R2 remains de-energized until the next 
sheet of substrate passes over the electric eye causing relay R2 to 
energize de-energizing the solenoid vacuum valve, allowing the tail of the 
first sheet to fall on the leading edge of the second sheet, completing 
the cycle. Relay R22 is controlled through a timer on press 22. When the 
press stops, R22 remains energized for one minute. 
When operating the accumulator in manual mode, relay R22 is not energized. 
To operate the accumulator, the start button is engaged, energizing relay 
R1 to energize the DC drive. Engaging the stop button de-energizes relay 
R1. 
The above description is considered that of the preferred embodiment only. 
Modifications of the invention will occur to those skilled in the art and 
to those who make or use the invention. Therefore, it is understood that 
the embodiment shown in the drawings and described above is merely for 
illustrative purposes and not intended to limit the scope of the 
invention, which is defined by the following claims as interpreted 
according to the principles of patent law, including the doctrine of 
equivalents.