Printing – Planographic – Dampeners
Patent
1996-05-29
1997-10-07
Yan, Ren
Printing
Planographic
Dampeners
101425, B41F 724
Patent
active
056736223
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for wetting and cleaning cylinders in an offset rotary printing machine of the type including a plate cylinder, an offset cylinder, and an impression cylinder as well as wetting cylinders running against the plate cylinder, said wetting cylinders being moistened from a number of nozzles in a ramp mounted in parallel to the rotational axis of the cylinders, by a moistening fluid, usually water, being sprayed from the nozzles towards one of the wetting cylinders in atomized condition. Each nozzle has an inlet for moistening fluid and an inlet for a cleaning liquid, and these inlets can be opened and closed individually by means of a solenoid valve in order to supply moistening fluid or cleaning liquid, respectively, through the nozzle. The solenoid valves are computer controlled in dependence of different operating parameters of the printing machine.
SUMMARY OF THE INVENTION
The purpose of the invention is to simplify the construction of the nozzle ramp by providing a compact and economical valve arrangement wherein the valves are able to open and close rapidly without bouncing causing residual spray, and wherein the period between zero flow and maximum flow is as short as possible. Then, pressure drops and pressure peaks which arise at the rapid opening and closing of the valves and which cannot be neglected shall be eliminated by pressure equalization in the conduit system to the inlets of the valves.
The purpose of the invention is also to provide adjustment of the valves at high speed and high timely precision without too much energy being dissipated in the valves.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to explain the invention in more detail reference is made to the accompanying drawings in which
FIG. 1 is a side view of a valve unit according to the invention,
FIG. 2 is a fragmentary vertical cross sectional view of the valve unit in FIG. 1,
FIG. 3 is an enlarged cross sectional view forming part of FIG. 2,
FIG. 4 is a horizontal cross sectional view of the valve unit in FIG. 1,
FIG. 5 is an enlarged axial cross sectional view of a solenoid armature having a valve element of rubber or rubber-like material,
FIGS. 6 to 9 are fragmentary views in reduced scale of the solenoid armature disclosing different functional positions, and
FIG. 10 is a diagram illustrating different parameters of the valve function.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The wetting ramp can comprise a number of nozzles e.g. twelve, arranged in a row each nozzle having two valves for controlling the supply of water (moistening fluid) and cleaning liquid to the nozzles. For each nozzle there is provided a valve housing 10, two solenoids 11 being connected to said housing. The valve housing straddles two conduits 12 and 13 one for supplying water and the other for supplying cleaning liquid, as shown in FIG. 2, and as will more clearly seen in FIG. 3 an aperture 14 is made in conduit 12. An O-ring 15 is provided around the aperture to seal between the valve housing and the conduit. Through the aperture, the conduit is connected with a passage 16 in valve housing 10, said passage in turn communicating with a passage 17 in valve housing 10. Conduit 13 is connected in a corresponding manner. A yoke 18 and the valve housing are mounted by means of a screw connection 19 on a support rail 20. A spray nozzle 21 is mounted in the yoke, communicating with a supply passage 22 which is connected to a passage 23 in valve housing 10 at the center of this latter passage.
Each end of passage 23 opens into a recess 24, and passages 17 open each into one of the two recesses. The armature 25 of each solenoid 11 has a plunger 26 displaceably guided therein, as well as a rubber element 27, FIG. 5, provided as a valve element. A compression spring 28 biases plunger 26 and armature 25, and also a compression spring 29 which is weaker than spring 28 biases the armature. By the bias of spring 28 rubber element 27 is kept engaged with the bottom of recess 24 and keeps the e
REFERENCES:
patent: 3764070 (1973-10-01), Glaser
patent: 4873925 (1989-10-01), Hultberg et al.
patent: 5025722 (1991-06-01), Switall et al.
patent: 5303652 (1994-04-01), Gasparrini et al.
patent: 5505126 (1996-04-01), Ohno et al.
Grafiskt Team AB
Yan Ren
LandOfFree
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