Printing – Multicolor – Rotary machines
Reexamination Certificate
1999-03-31
2001-09-04
Asher, Kimberly L. (Department: 2854)
Printing
Multicolor
Rotary machines
C101S185000, C101S184000, C101S247000
Reexamination Certificate
active
06283024
ABSTRACT:
TECHNICAL FIELD
This invention relates to printing presses and, more particularly, to central impression flexographic printing presses having quick change print stations and upstream side print station doctor blades.
BACKGROUND
Central impression printing presses, which have been used for many years, are characterized by a central impression cylinder with a plurality of print stations spaced around the central impression cylinder. Each print station typically includes a meter roll, an anilox roll, and a print roll. These types of printing presses are preferred because they maintain relatively precise registration of the printed material. Typical central impression presses include three to eight print stations and have a web width ranging from approximately four to sixty inches. To support the central impression cylinder and the print stations while maintaining registration with the desired precision, central impression presses utilize substantially fixed and continuous opposing side walls to support the central impression cylinder and the print stations. The side walls typically enclose the sides of the print stations thereby substantially inhibiting access to the central impression cylinder and the print stations.
At several points during a printing process and at the conclusion of a printing job, the printing press operator must clean and/or change the rolls in one or more of the print stations. In currently available central impression presses, it takes an inordinate amount of time to remove the anilox and meter rolls for cleaning or replacement with different rolls for a different job. Because it takes so long to remove the rolls for cleaning or to change the rolls, operators are encouraged to risk potentially severe injury by cleaning the rolls while they are still in the press, and occasionally operators sacrifice print quality by not changing the rolls when required for the next printing job.
More specifically, when cleaning the rolls while in the press, operators risk pinching their fingers between rolls. To clean rolls around their entire circumference, operators jog, that is incrementally rotate, the rolls or leave the rolls rotating while holding a cloth against the roll with their hands. As expected, cloths and fingers occasionally get caught between rolls, and when a finger gets caught, the finger is severely injured or even lost. As to print quality, cleaning the rolls with cloths is not as effective as rinsing them in wash basins. Also, anilox rolls are provided with different cell configurations and concentrations to control the amount of ink that is transferred to the print roll for application to the web which passes between the central impression cylinder and the print rolls. If the anilox roll already in the press is close in cell configuration and concentration to the anilox roll required for the next print job, operators are tempted to save time by using the anilox roll from the previous print job thereby diminishing the print quality.
Doctor blades are also used to further improve print quality by more accurately metering the amount of ink transferred to the print rolls. The doctor blades scrape against the anilox rolls to remove excess ink. For doctor blades to be effective, they must be positioned between the meter rolls and the print rolls to scrape the anilox rolls after they are inked by the meter rolls and before the anilox rolls transfer their ink to the print rolls. For print stations on the downstream side of the central cylinder, the doctor blades are positioned opposite to the central cylinder, but for print stations on the upstream side of the central cylinder, the doctor blades must be positioned between the print station and the central cylinder. Thus, the upstream doctor blades would be inaccessible to an operator making it commercially unfeasible to use doctor blades on upstream print stations.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide an improved quick change print station.
It is another object of the present invention to provide an improved central impression press having quick change print stations.
It is still another object of the present invention to provide an improved upstream print station assembly having a doctor blade.
It is a further object of the present invention to provide an improved print station which reduces the risk of injury.
In carrying out the foregoing and other objects, the present invention contemplates an improved quick change print station for a central impression printing press. The press includes a central impression cylinder and at least two quick change print stations. The quick change print stations include a plurality of rotating rolls with at least one of the rolls mounted on a movable carriage which is movable between retracted and operative positions.
In a preferred embodiment, the press has substantially fixed and continuous side walls, and the movable carriages are retracted in a direction substantially parallel to a longitudinal axis of the press. Preferably, each carriage holds an ink tray, an anilox roll, and a meter roll. The carriages include anilox roll mounts which are preferably less than half a circle and meter roll mounting slots which are open at one end allowing both the anilox roll and the meter roll to be simply lifted off the carriage. When the carriages are in the operative positions, the anilox rolls are held in place by bearing stops extending from bushings mounted in the side walls of the press. The anilox rolls are driven by engagement of a shear pin which shears off if a finger or a cloth become caught in the rolls. The carriages are locked in place by lock mechanisms which utilize lock arms with engagement surfaces configured to progressively engage cylindrical lock shafts of the carriages and urge the carriages into their operative positions. Each print station is also provided with a guide track assembly having a fixed guide track and a removable guide track extension.
The invention also contemplates use of an upstream doctor blade on an upstream print station of a central impression printing press. The doctor blade is preferably positioned between the central cylinder of the press and the anilox roll and engages the anilox roll after the anilox roll is inked by the meter roll but before the anilox roll transfers ink to the print roll. The upstream doctor blade is preferably provided with two adjustments; one of the adjustments allows the blade to be adjusted without moving the carriage.
The invention further contemplates using the described quick change print stations in a method for cleaning or changing components of a printing press print station. The method is performed by unlocking a movable carriage, moving the carriage to a retracted position, and lifting the anilox roll off the carriage. Preferably, the meter roll is also lifted off the carriage for cleaning. The carriage is preferably rolled to the retracted position.
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“FLEXOGRAPHY: Principles and Practices”, Flexographic Technical Association, Inc., 1rst ed., 1962.
Asher Kimberly L.
Blackwell Sanders Peper Martin LLP
Elliott Kyle L.
Express Card & Label Co., Inc.
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