Printing – Rolling contact machines – Rotary
Reexamination Certificate
2000-02-08
2001-09-18
Yan, Ren (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S218000
Reexamination Certificate
active
06289805
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to printing presses and more particularly to a device and method for driving a printing cylinder in a printing press.
2. Background Information
Printing cylinders of printing presses print a material, such as paper. In offset web printing, the printing cylinders include a plate cylinder and a blanket cylinder. Typically, a plate on the plate cylinder engages the blanket on the blanket cylinder, as a web or sheet of material passes between the blanket and an impression cylinder. Ink is transferred from an ink roller to the plate cylinder, and ink corresponding to an image is transferred to the blanket and then to the web or sheet. For two sided printing, the impression cylinder is another blanket cylinder.
The plate and blanket cylinders are driven on a gear side of a printing press by a drive mechanism, which typically comprises gearing for driving each of the printing cylinders. A single or multiple motors can power the drive mechanism. Hitachi-Seiko, for example, has a two motor drive for driving two printing cylinders in a four-cylinder printing unit. Heidelberg Web Press, Inc. has a three motor drive for driving three printing cylinders of a four cylinder printing unit.
In order to prevent wrap-up during a web break in web printing presses, or to change plates or blankets on the respective cylinders, it is sometimes necessary to throw-off the plate cylinder from the blanket cylinder, and also to throw-off the blanket cylinder from the impression cylinder. The mechanisms which move the printing cylinders are called throw-off mechanisms.
Because the plate and blanket cylinders still need to rotate during throw off, the drive mechanism must remain engaged during throw-off.
U.S. Pat. No. 5,678,485 purports to disclose an offset printing press having a counterpoise and lift mechanism. The counterpoise is provided for permitting an axial blanket or printing sleeve to be slid over a respective cylinder. The lift mechanism is a throw-off mechanism for throwing-off, for example, the plate cylinder. A drive mechanism is not disclosed.
U.S. Pat. No. 3,724,368 purports to disclose a drive mechanism and a throw-off mechanism for an offset printing press. An harmonic drive means provides for register adjustment of both plate cylinders. The primary drive for the printing press is provided through a motor connected to one of the blanket cylinders.
The printing press manufacturer MAN Roland has a direct drive for a blanket cylinder. The motor is moved during throw-off and the motor drives the blanket cylinder in a 1:1 ratio.
One problem with the above-devices is that the motors to drive the cylinders are large and space-consuming, and are often difficult to adjust. Moreover, the motors often must be moved along with the cylinders during throw-off, which can create a complicated and difficult structure.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to permit smaller drive motors for printing cylinders and to permit the motors to operate at higher speeds. A further or alternate object of the present invention is to permit the motor to be fixed, even during throw-off.
The present invention thus provides a printing press including a printing cylinder and a printing cylinder drive, the drive including a drive motor connected to a sun gear, a planet gear rotating about a fixed axis and driven by the sun gear, and a ring gear fixedly attached to the printing cylinder and driven by the planet gear.
The planetary gear arrangement of the present invention permits the use of higher speed motors, since the sun gear rotates at a higher rotational speed than the ring gear. A lower inertial ratio on the motor may thus be maintained. The use of higher motor speeds also permits better electronic control of the speed of the printing cylinder.
Preferably, the printing cylinder is a blanket or plate cylinder of an offset printing press.
Also preferably, the printing cylinder has a first position in which the printing cylinder is engaged for printing and a second position in which the printing cylinder is thrown-off. The motor remains in a same position during both the first and second positions of the printing cylinder, while the ring gear moves with the printing cylinder, but remains engaged with the planet gear.
The use of a fixed motor is highly advantageous, in that it becomes much easier to throw-off the cylinder if the motor does not also need to be moved.
The printing press also preferably includes a throw-off device connected to the printing cylinder, the throw-off device including a pivotable lever for moving the printing cylinder.
The printing cylinder may be gapped or preferably may be cantileverable, so that a sleeve such as a gapless blanket or gapless plate may be slid over one end of the printing cylinder.
The gear ratio provided by the planetary gear arrangement preferably is four-to-one, i.e. the sun gear and motor rotate at four times the rotational speed of the ring gear and printing cylinder.
Preferably, the printing cylinder is a plate cylinder of an offset printing press also including a blanket cylinder, the blanket cylinder being driven by a drive gear connected to the ring gear, the drive gear connected to a driven gear fixedly attached to the blanket cylinder. If the blanket and plate cylinders are 1:1 in size, the drive gear is preferably the same size as the driven gear.
The planet gear preferably has an anti-backlash design. The planetary gear arrangement also may have a uniflank arrangement to minimize backlash.
The motor could be arranged to slide axially coupled with helical gearing to provide circumferential movement for registering the printing cylinder. Alternatively, the circumferential register can be provided through the drive motors.
The present invention also provides a method for driving a printing cylinder comprising the steps of:
driving a sun gear using a drive motor, the sun gear driving a planet gear and a ring gear, the ring gear being fixedly attached to the printing cylinder.
Preferably, the method further includes throwing off the printing cylinder while keeping the drive motor stationary.
REFERENCES:
patent: 3721130 (1973-03-01), McKee
patent: 3724368 (1973-04-01), Treff
patent: 3960079 (1976-06-01), Capetti
patent: 4309945 (1982-01-01), Marion
patent: 4953461 (1990-09-01), Gaffney et al.
patent: 5357858 (1994-10-01), Guaraldi et al.
patent: 5678485 (1997-10-01), Guaraldi
U.S. Patent application Ser. No. 09/165,621 filed Mar. 10, 1999.
U.S. Patent application Ser. No. 08/979,108 filed Nov. 26, 1997.
Douillard Gerald Roger
Dumais Mark Bernard
Lemellin Michael Robert
Davidson Davidson & Kappel LLC
Heidelberger Druckmaschinen AG
Yan Ren
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