Printing – Inkers – Fountains
Reexamination Certificate
1999-12-22
2003-02-11
Eickholt, Eugene H. (Department: 2854)
Printing
Inkers
Fountains
C101S366000
Reexamination Certificate
active
06516721
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an inking unit for a printing machine, which includes one or more distributor drums, ink transfer rollers, ink application rollers, an ink reservoir for printing ink and an ink metering device having at least one electrically controllable valve for metering the printing ink. The invention also relates to a method for supplying printing ink to a printing machine.
A conventional inking unit for an offset printing press is shown in FIG.
7
. The inking unit includes an ink fountain
122
serving as a reservoir for printing ink
124
, an ink fountain roller
126
, an ink feed roller
128
and a roller arrangement which, in this conventional embodiment, includes four distributor drums
130
a
to
130
d,
four ink applicator rollers
132
, which roll on a plate cylinder
134
of the printing machine, and a number of ink transfer rollers
136
. The demand or requirement for the printing ink
124
is set or adjusted zonewise as a function of or in accordance with the printing image by pressing a sprung blade (ink fountain blade)
125
more-or-less strongly against the ink fountain roller
126
, and thereby varying the ink quantity that passes through the gap between the ink fountain blade
125
and the ink fountain roller
126
. Regulation of the printing ink
124
over the entire width of the ink fountain roller
126
is performed by varying the ink removing stripe that is lifted from the ink fountain roller
126
by the ink feed roller
128
in a rhythmic oscillating movement. The printing ink
124
is repeatedly distributed and divided by the downline arrangement of hard and soft rollers of various diameters, and distributed by an axial movement of the distributor drums
130
a
to
130
d
before it is applied to the plate cylinder
134
by the ink applicator rollers
132
.
The aforedescribed arrangement permits only relatively imprecise ink metering which is yet further worsened by wear in the ink metering region, with the result that a large number of rollers are required to achieve the necessary low ink film thickness. The ink feed can be reproduced only with difficulty. Subassemblies such as that formed of an ink fountain, an ink fountain roller and ink feed roller require a relatively large amount of space and have to be cleaned regularly. In order to automate the ink metering, which is normally performed manually, electric actuating and control elements are required in addition to the elements described hereinabove. There is also a need for a squeegee device to remove excessive printing ink. Heretofore known methods for solving these problems call for the use of ink cartridges, for example, as a result of which only the manual ink feed is eliminated, or for the use of low-wear materials for the ink metering region, which likewise only partially solves the described problems.
The journal Zeitungstechnik, July/August 1996, page 30, displays an inking unit of the type described in the introduction hereto, wherein the printing ink is applied to a specifically constructed ink film roller with the aid of a digital ink pumping system which includes a gear pump and solenoid valves which are under pulse-length control. It is true that the ink metering is performed more precisely than with ink fountain systems, but there is a need for a squeegee or doctor blade device for removing excessive ink.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an inking unit for a printing machine with an ink metering device that permits extremely precise ink metering, the inking unit having a simple and space-saving construction and being derivable from a conventional inking unit by simple structural changes. It is a further object of the invention to provide a method of supplying ink to a printing machine that is an improvement over heretofore known methods of this general type.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, an inking unit for a printing machine, including at least one distributor drum, ink transfer rollers, ink application rollers, an ink reservoir for printing ink and an ink metering device having at least one electrically controllable valve for metering the printing ink, comprising a high-pressure pumping device for supplying the printing ink metering device with printing ink at a predetermined high pressure from the ink reservoir, and a heating device for heating the printing ink to a predetermined temperature above room temperature, the at least one valve of the ink metering device having a short reaction time and a flow rate with a low dependence upon viscosity.
In accordance with another feature of the invention, the at least one valve includes piezoelectric actuators.
In accordance with a further feature of the invention, the at least one valve includes a spherical sealing element disposed opposite a spherically recessed valve seat wherein an opening having a substantially smaller diameter than that of the spherical sealing element is formed.
In accordance with an added feature of the invention, the printing ink, at room temperature and a low shear rate, has a dynamic viscosity of more than 10 pa s (pascal seconds), the pumping device being capable of producing a pressure in the range of approximately 10 to 100 bar, and the temperature of the printing ink heated by the heating device being in a range of approximately 40° C. to 70° C.
In accordance with an additional feature of the invention, the ink metering device includes a row of nozzles directed onto the surface of one of the distributor drums.
In accordance with yet another feature of the invention, a respective valve is provided for each ink zone, the valve having an outlet connected to at least one nozzle disposed in the respective ink zone.
In accordance with yet a further feature of the invention, the ink reservoir is one of an ink cartridge and a bulk container, respectively.
In accordance with yet an added feature of the invention, the inking unit includes a valve for supplying cleaning liquid for the purpose of cleaning the ink metering device.
In accordance with yet an additional feature of the invention, the ink metering device is provided for the purpose of spraying cleaning liquid onto a distributor drum.
In accordance with another aspect of the invention, there is provided a method for supplying printing ink to a printing machine, the printing ink being metered by at least one electrically controllable valve, which comprises feeding the printing ink to the at least one valve at a predetermined high pressure and at a predetermined temperature above room temperature, the printing ink being metered free of excess in the printing machine in accordance with the demand therefor.
In accordance with another mode, the method of the invention includes providing a printing ink which, at room temperature and a low shear rate, has a dynamic viscosity of more than 10 Pa s, pressurizing the printing ink in the range of approximately 10 to 100 bar, and heating the printing ink to a temperature in the range of approximately 40° to 70° C.
In accordance with a further mode of the method, the at least one valve has a reaction time in the order of magnitude of microseconds, and the method further includes metering the ink by opening and closing the at least one valve under pulse-length control.
In accordance with a concomitant mode, the method of the invention includes spraying the printing ink out of synchronism with the machine time cycle onto a distributor drum of the printing machine so that, with one of each distributor stroke and each distributor revolution, respectively, the printing ink is applied offset temporally relative to the machine time cycle.
Thus, the inking unit according to the invention permits the use of a standard offset printing ink which, at room temperature and a low shear rate, has a dynamic viscosity of more than 10 Pa s, for example 50 to 70 Pa s. By virtue of the fact that the printing ink is fed to the at least one valve at a pre
Eickholt Eugene H.
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Locher Ralph E.
Mayback Gregory L.
LandOfFree
Inking unit for a printing machine and method for supplying... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Inking unit for a printing machine and method for supplying..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Inking unit for a printing machine and method for supplying... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3164636