Printing – Processes – With heating or cooling
Reexamination Certificate
2000-07-07
2001-09-25
Asher, Kimberly L. (Department: 2854)
Printing
Processes
With heating or cooling
C101S216000, C101S349100
Reexamination Certificate
active
06293199
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to printing press circulation systems, and, more particularly, to a water pan having a dedicated power return drain and optional cooling capability located on and as part of the pan.
2. Description of Related Art
In a conventional printing press liquid circulating system, a cylindrical pan roller is partially immersed in a refrigerated or non-refrigerated liquid which is contained in a cooling pan. The pan roller is rotated to pick up the appropriate amount of cooled liquid from the pan and distribute a uniform film of liquid to the dampening system of the press.
FIG. 1
illustrates a conventional liquid circulating system. As illustrated in
FIG. 1
, a conventional liquid circulating system includes a circulator
110
housing a tank or reservoir (not shown) for storing the liquid and a compression refrigeration circuit (not shown) typically utilizing R
12
, R
22
or R
134
A refrigerant (adopted for environmental reasons), and a pump
112
.
The compression refrigeration circuit cools the liquid that is sent to either a single pan
120
or multiple pans on the printing press. The liquid fills the pan(s)
120
to a level determined by either a removeable standpipe or dam
124
.
A supply conduit
114
extends between the circulator
110
and the pan
120
and provides for a relatively constant flow of liquid into pan
120
. Liquid is forced through supply conduit
114
by the circulator pump
112
which is driven by an electrical motor or equivalent (not shown).
The standpipe
124
of the cooling pan drains the liquid to a liquid return conduit
116
. Return conduit
116
directs the liquid back to the tank or reservoir in the circulator
110
. The liquid continuously flows through the pans (while removing heat from the press) and enters the return conduit
116
by flowing over and into the standpipe drain
124
. In some cases, the return flow is simply drained by gravity back to the circulator tank or reservoir. However, most pan drain hole sizes and the return line routing provisions (i.e. space, bends, and conduit paths) do not permit for simple gravity return.
The pump
112
pumps liquid through the supply conduit
114
to supply the pan with a cooling liquid and to circulate the liquid through the pan to the return conduit
116
. The pump supplies liquid through the supply conduit
114
and a branch supplies the power drain to create a suction pressure (i.e. a pressure below atmospheric pressure) that is induced in the portion of the return conduit
116
between the pan
120
and the circulator
110
.
Traditionally, the liquid has been cooled at the circulator
110
by the compression refrigeration circuit and then pumped to the pans
120
. However, by the time the liquid reaches the pan
120
, losses in cooling capacity have occurred during the transport phase through the supply lines
114
. This reduction in cooling capacity reduces the ability of the liquid to remove the heat generated by the press operation.
Conventional circulators
110
have also been provided with a return line power drain
118
at the circulator
110
to create a vacuum in the return line
116
to assist return flow. For proper operation, the power drain
118
must provide a vacuum that allows for only liquid return from the standpipe
124
entry position. Too much vacuum, however, will cause foaming in the tank or reservoir as air will be drawn in, and too little vacuum will cause the pan to overflow.
With the power drain located at the circulator, the system uses cooled flow to operate the power drain. Approximately 40% to 80% of the pump output is used as motive flow for the power drain. However, as mentioned above, losses in cooling capacity occur during the transport phase through the supply lines.
A large number of press manufacturers produce a variety of presses, each having different size pan return holes, conduit lengths and shapes, space, required bends, and varying conduit return paths, creating a matrix of varying return flow conditions which cannot be handled properly with the present circulator power drains. Each pan system can have different return line lengths, bends and return line paths. Additionally, in a multiple pan system with a single power drain, ink debris in one return path will cause an imbalance and cause the return on one to flood while the rest foam.
Normally, one or more power drain sizes are used to cover this varying range by circulator manufacturers. However, these systems are hard to balance by flow control means to the power drain and are very troublesome when two or more pans are connected to only one power drain. Various attempts to control the power drain function, such as that disclosed in U.S. Pat. No. 4,300,450 to Gasparrini, have been made, but the basic problems still exist.
Another problem with power drains located at the circulator is that one return line is required for each pan to return the liquid back to the circulator tank or reservoir. These current circulating systems place limitations on the installation of conduits, resulting in unprofessional arrangements.
Thus, there exists a need for an improved printing press liquid circulating system that provides improved drain flow creating a balanced system, improved cooling capacity, ease of installation, and a more effective pan design.
SUMMARY OF THE INVENTION
The present invention satisfies such a need. A printing press circulation system according to one embodiment of the present invention comprises at least one pan for supplying liquid to a printing press. Each pan includes a liquid supply orifice and an outlet. A standpipe is disposed in communication with the outlet of the pan and configured to drain liquid from the pan while maintaining a substantially constant liquid level in the pan. The circulation system also includes a reservoir holding the liquid and a power drain corresponding to each pan. Each power drain includes a first inlet having a power drain orifice, a second inlet and an outlet. A drain conduit extends from the standpipe of the pan to the second inlet of the power drain for draining liquid from the pan. A return conduit extends from the outlet of the power drain to the reservoir. A pump is configured to pump liquid from the reservoir through a supply conduit to the pan liquid supply orifice and the first inlet of the power drain to draw liquid from the pan and by inducing suction in the return conduit.
In another embodiment of the present invention, a printing press circulation system comprising at least one pan for supplying liquid to a printing press, each pan including a liquid supply orifice and an outlet. A standpipe is disposed in communication with the outlet of the pan. The standpipe is configured to drain liquid from the pan while maintaining a substantially constant liquid level in the pan. A reservoir for holding the liquid is also provided. A power drain corresponds to each pan, each power drain including an inlet having a power drain orifice and an outlet. A cooling mechanism corresponding to each pan is provided. Each cooling mechanism is located in proximity to the corresponding pan. A drain conduit extends from the power drain orifice of the power drain for draining the cooling mechanism and the standpipe. A return conduit extends from the outlet of the power drain to the reservoir. A pump is configured to pump liquid from the reservoir through a supply conduit to the liquid supply orifice and the cooling mechanism to induce a suction pressure in the return conduit to draw liquid from the pan to the return conduit.
In yet another embodiment, a printing press circulation system comprising at least one pan for supplying liquid to a printing press, each pan including an inlet and an outlet. A standpipe is disposed in communication with the outlet of the pan. The standpipe is configured to drain liquid from the pan while maintaining a substantially constant liquid level in the pan. The circulation system also comprises a reservoir for holding the liquid and a cooling mechanis
Gasparrini Charles R.
Hickey Christopher
Asher Kimberly L.
Baldwin GraphicsSystems, Inc.
Crenshaw M.
Morgan & Finnegan , LLP
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