Printing – Processes – With heating or cooling
Reexamination Certificate
1999-07-22
2003-01-14
Eickholt, Eugene H. (Department: 2854)
Printing
Processes
With heating or cooling
C101S216000, C101S350100, C101S350300
Reexamination Certificate
active
06505557
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to process temperature control for a rotary process machine such as a printing press.
DESCRIPTION OF THE RELATED ART
Rotary printing presses are utilized to reproduce copies of an original copy at a reasonable cost in a rapid and semi-continuous manner by applying ink of assorted colors in a pre-determined “dot” array laid down on a substrate, such as paper, from printing plates. Typically, four process ink colors are utilized in a printing run necessitating, at least, four units of press, one for each ink color. The “dot” array of each ink color is super-imposed adjacent to the other ink colors so that no ink color dots touch each other. This creates an optical image in color, shade and tone of an original. There are various types of rotary printing machines using different printing processes such as gravure, flexography and lithography. Since lithography is the most common printing process used today, this description of the related art and the present invention will focus on the lithographic printing process. However, the related art and the present invention applies to any rotary press process where process fluids, such as ink and dampening solution are utilized.
In lithography, there are two types of printing plates utilized, namely, water based and waterless. Whether this predetermined “dot” array of each ink color is achieved by using conventional lithographic printing plates with oleophilic and hydrophilic areas, the water based type, or waterless printing plates that do not require the water dampening in the conventional lithography process, narrow process temperature control is vital to obtain and maintain consistent quality of each copy produced. Today, printing presses operate at a rate as high as 25 copies per second with so called web rotary offset presses and 5 copies per second with so called sheet-fed offset rotary presses. Once a copy is produced, it is either saleable or waste. The quality of each copy is influenced by many factors such as the typed, adjustment and condition of the rotary press, its accessories equipment, ink, paper and press operator skills. A further very important factor at high press speeds is process temperature control. Effective process temperature control is a real-time issue requiring very fast and accurate process temperature monitoring and adjustments at every instant during each print run. A printing run, defined as the time it takes to generate a desired number of good copies of a specific original, is a pressroom process of setting up the press for this specific print run (make ready), then ramping the speed of the rotary press as quickly as possible while producing a minimum of wasted copies. A print run often involves frequent press stoppages to deal with an assortment of printing problems. Whereas rotary press heating is important for cold press startups, controlled process temperature cooling is continuously important once the press is up to temperature to deal with the process and friction heat loads generated at each press unit. Machine friction heat increases exponentially with press speeds. Process heat loads are generated by ink shearing that takes place at higher press speeds. Prior art in the field of press temperature control ignores the real-time issue of meaningful process temperature control and focuses mostly on general cooling of the rotary press using ink vibrator roller cooling. The paradyns of the printing industry accept this non real-time process general cooling as sufficient. It relies on operator skills to visually inspect copies produced to observe all print quality drifts with which he or she makes appropriate process adjustments. This procedure deals with the real-time effects of process temperature changes rather than treating the cause to eliminate print quality drifts before they occur. The prior art attempts to cool the printing process generally and ink specifically, but makes no attempt to use ink or other process fluids as a coolant towards achieving a more rigid control over process temperatures. Further, and more importantly, the prior art makes no attempt to reach quickly to changes in process temperatures as they continuously occur during each print run. This present invention is dedicated to real-time process temperature control to provide direct control of the color quality of each copy produced.
U.S. Pat. No. 2,971,460 issued to Shindle in 1961 discloses a system for controlling ink roller temperatures of a printing press by circulating cold or hot water through these hollowed out rollers. The purpose of this art is to cool or heat these rollers using water which discharge to a drain using a thermostatic valve that is responsive to the water temperature discharged from these rollers. In addition to its wastefulness of water, no attempt is made, or envisioned, to directly control process temperatures of the press. Rather, this art satisfies its purpose of removing of some of the printing process heat gain in a manner that only responds to the temperature gain or losses of the water to drain. No attempt is made, or contemplated, to directly measure or control any printing process temperature.
U.S. Pat. No. 3,956,986 issued to Burkhandt Wirz et al in 1976 discloses a system to provide control of the temperature of the ink fountain roller and ink vibrator rollers by circulating water through these rollers such that the water discharged from these rollers can be heated or cooled to a preset temperature by adding hotter or colder water before recirculating same back to the press. While this art automates that which was envisioned by U.S. Pat. No. 2,971,460 granted to Shindle in 1961, this art does not attempt or envision to directly monitor or control ink temperatures or other process temperatures.
U.S. Pat. No. 5,272,971 issued to Guenther Fredericks in 1993 discloses a system to provide ink temperature control for lithographic printing by using a non contact sensor at the ink vibrator rollers and at the plate cylinder roller to operate a PID controlled valve which adds cool and hot water to the coolant supplied to the printing press to achieve a preset temperature for delivery to the vibrator rollers of a press. While the inventor of this art claims that this method of controlling the coolant temperatures is substantially continuous, rapid and energy efficient, this art cannot be quicker to maintain process temperatures than the speed at which the coolant temperature is adjusted by the addition of cool or hot water. As a result, this art is too slow to control the process temperature of the ink at the ink vibrator rollers in real time and even more slow to adjust process temperature control at the plate cylinder of a printing press where no coolant is circulated.
U.S. Pat. No. 5,189,960 issued to Frederic Valentine in 1993 discloses a system for controlling the temperature of the printing plates on the plate cylinders of a rotary printing press using closed loop heater and cooler units with controllable mixing valves to provide a desired temperature coolant fed to the ink oscillator rollers of a printing press. The controlled coolant mixture cools or heats the ink and in turn, the ink cools the printing plate at the plate cylinder. This art is a system similar to U.S. Pat. No. 5,272,971 in that it attempts to control the ink temperature at the ink vibrator rollers using a controllable mixing valve, non contact temperature sensor and a temperature controller to automate the temperature control process. This art is also too slow acting to provide process temperature changes in real time.
U.S. Pat. No. 5,611,278 issued to Steve M. Garner in 1997 discloses a system that controls the ink temperature of a printing plate and ink vibrator rollers of a printing press using non contact sensors interfaced to an electrically operated valve placed in the coolant flow circuit to and from the ink vibrator rollers. This art envisions achieving process temperature control by varying the coolant flow rate to the press in real-time. The electrically operate
Desaulniers Ted
Lovaghy John
Eickholt Eugene H.
Fincham Eric
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