Printing – Antismut device – Anti-offset material application
Reexamination Certificate
1999-11-16
2001-06-26
Hilten, John S. (Department: 2854)
Printing
Antismut device
Anti-offset material application
C101S416100, C118S309000, C118SDIG001, C239S654000
Reexamination Certificate
active
06250224
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates powder sprayers in printing presses.
BACKGROUND OF THE INVENTION
Offset printing presses can produce several hundred sheets of printed material per minute. In most cases, the ink is still tacky when the printed sheets come from the printing press so that when the sheets are stacked together the ink from each of the printed sheets may be partially transferred to or it may adhere to the backside of an adjacent sheet. Thus, powder is often sprayed onto the sheets prior to stacking the sheets to prevent the transfer of ink. The powder also facilitates movement of the sheets by an operator by reducing the friction between the stacked sheets.
Laverick, U.S. Pat. No. 4,622,896, discloses a powder spray gun attachment for a sheet delivery tray of a printing press.
Schmoeger, U.S. Pat. No. 4,332,198, discloses an air assist powdering system having a solenoid valve for actuating the powdering system.
SUMMARY OF THE INVENTION
One aspect of the invention features a powder sprayer unit which provides improved spraying of powder onto printed sheets of material produced in printing presses. This aspect of the invention generally includes a source of pressurized fluid, a source of powder, a mixer and a distributor. The mixer includes at least one fluid inlet positioned to receive fluid from the fluid source, and at least one powder inlet positioned to receive powder from the source of powder. The mixer mixes the fluid and the powder forming a fluid/powder mixture. The distributor includes a disperser positioned to disperse the mixture as it flows to a plurality of nozzles. The nozzles are positioned to spray the dispersed mixture onto specified areas of printed sheets of material.
Among other advantages, the powder sprayer unit of the present invention is able to uniformly spray the air/powder mixture onto sheets of material without forming local accumulations of powder on the sheets.
Embodiments of this aspect of the invention may include one or more of the following features.
The distributor may be a distribution chamber, and the mixer may include a mixing chamber having an outlet providing the mixture to an inlet for the distribution chamber. The disperser may be positioned near the inlet of the distribution chamber. The distributor may also include a plurality of outlets in flow communication with the nozzles. The outlets may be connected to the nozzles with cylindrical tubes.
The mixer may include a rotatable cylindrical roller that effectuates the mixing of the fluid and powder to produce the fluid/powder mixture. The roller may be rotated by a motor. A sensor may be included in such an arrangement to detect inadvertent stoppage of the motor, so that an alarm is activated indicating the stoppage of the motor.
A powder reservoir may be used as the source of powder. A detector may be used to detect low levels of powder in the reservoir; preferably, the detector is a fiber optics detector.
The printed sheets of material may be stacked in a stacking area, and, preferably, the powder prevents the transfer of printed matter between adjacent printed sheets of material. The powder may also facilitate movement of adjacent printed sheets of material.
The above described powder sprayer unit may be used in a method to spray powder onto printed sheets of material having passed through a printing press.
Other features and advantages of the invention will become apparent from the following description and drawings.
REFERENCES:
patent: 697374 (1902-04-01), Stuart et al.
patent: 2093995 (1937-09-01), Blow
patent: 2703551 (1955-03-01), Daniels
patent: 2817310 (1957-12-01), Ponzini
patent: 3606087 (1971-09-01), Ortman
patent: 3764070 (1973-10-01), Glaser
patent: 4332198 (1982-06-01), Schmoeger
patent: 4622896 (1986-11-01), Laverick
patent: 4867063 (1989-09-01), Baker et al.
patent: 5090626 (1992-02-01), Platsch
patent: 5713285 (1998-02-01), Reed et al.
patent: 222061 (1990-01-01), None
Grafix product brochure.
Weko product brochure.
DiRico Mark A.
Hofmann Hans J.
Grohusky Leslie J.
Hilten John S.
Thomas Kayden Horstemeyer & Risley LLP
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