Presses – Safety device – Means to disable or to forestall power to the press
Reexamination Certificate
1999-07-23
2001-07-10
Gerrity, Stephen F. (Department: 3721)
Presses
Safety device
Means to disable or to forestall power to the press
C100S170000, C100S171000, C101S216000, C101S483000
Reexamination Certificate
active
06257134
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a method and a device for safeguarding or protecting against penetration by foreign bodies into a roller nip, more particularly, between two cooperating cylinders, such as a contact-pressure roller cooperating with a plate cylinder in a printing press, in a manner that an automatically or semiautomatically supplied printing plate is mounted error-free on the plate cylinder and, in particular, a canted or bent trailing edge of the printing plate is introduced into a clamping and/or lock-up device for the printing plate.
A device of this general type has become known heretofore from the published German Patent Document DE 42 18 602 A1. In this known device, a contact-pressure roller corresponding in length to the length of the plate cylinder is provided, and is positionable against the plate cylinder by spring force. The spring force is applied by spiral compression springs, which have force action lines extending virtually radially to the plate cylinder. This known device has a protective function, in that a foreign member, such as a finger or hand, which may accidentally slip in between the contact-pressure roller and the plate, can displace the contact-pressure roller counter to the spring force of the spiral compression springs. A switch lever is connected to the contact-pressure roller via the shaft of the contact-pressure roller and, whenever the contact-pressure roller is deflected, actuates a switch that turns off the drive for the plate cylinder.
A disadvantage of the device disclosed in the aforementioned published German Patent Document DE 42 18 602 A1 is that the force causing the deflection of the contact-pressure roller increases as the distance traversed in the deflection increases, and can exceed an allowable distance; another disadvantage is that this force is exerted constantly on the foreign member, i.e., a finger or hand, for example.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a method and device for guarding against penetration by foreign bodies into a cylinder nip, wherein the force required for deflecting the contact-pressure roller is reduced to a permissible extent, and the continuous application of the force to the foreign body is also reduced or even eliminated.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method for safeguarding against the entry of foreign bodies into a nip between two cylinders, which comprises applying a deflection movement to one of the cylinders counter to a spring force applied thereto so as to overcome the spring force; and keeping the spring force to be overcome constant in accordance with a prescribed deflection distance.
In accordance with another aspect of the invention, there is provided a method for safeguarding against the entry of foreign bodies into a nip between a plate cylinder and a contact-pressure roller disposed parallel thereto and cooperating therewith, which comprises applying a deflection movement to the contact-pressure roller counter to a spring force applied thereto so as to overcome the spring force; and keeping the spring force to be overcome constant in accordance is with a prescribed deflection distance.
In accordance with a further aspect of the invention, there is provided a method for safeguarding against the entry of foreign bodies into a nip between two cylinders, which comprises applying a deflection movement to one of the cylinders counter to a spring force applied thereto so as to overcome the spring force; and reducing the spring force in accordance with a prescribed deflection distance.
In accordance with an added aspect of the invention, there is provided a method for safeguarding against the entry of foreign bodies into a nip between a plate cylinder and a contact-pressure roller disposed parallel thereto and cooperating therewith, which comprises applying a deflection movement to the contact-pressure roller counter to a spring force applied thereto so as to overcome the spring force; and reducing the spring force in accordance with a prescribed deflection distance.
In accordance with an additional aspect of the invention, there is provided a device for safeguarding against the entry of foreign bodies into a nip between a plate cylinder and a contact-pressure roller disposed parallel thereto and cooperating therewith, comprising a movable actuating element formed with a control contour having an ascending incline and, adjoining the ascending incline, a contour segment selected from the group thereof consisting of a straight edge and a descending incline; the contact-pressure roller being formed with ends in cooperative engagement with the control contour.
In accordance with yet another feature of the invention, the device includes guides disposed at respective ends of the contact-pressure roller for displaceably supporting the contact-pressure rollers.
In accordance with yet a further feature of the invention, the device includes an adjusting element, the guides being disposed so as to be adjustable by the adjusting element.
In accordance with yet an added feature of the invention, the contact-pressure roller is formed of a contact-pressure roller body rotatably supported on a shaft.
In accordance with yet an additional feature of the invention, the actuating element is disposed so as to be deflectable counter to the force of a restoring spring and is bringable into operative engagement with a switch.
In accordance with still another feature of the invention, the actuating element is disposed so as to be displaceable in axial direction of the contact-pressure roller.
In accordance with still a further feature of the invention, the actuating element is disposed so as to be displaceable at an angle to the shaft of the contact-pressure roller.
In accordance with still an added feature of the invention, the angle is a right angle.
In accordance with still an additional feature of the invention, the guides form part of the actuating element, and the control contours are disposed in the guides so that they are in mirror symmetry with one another.
In accordance with a concomitant feature of the invention, the guides, respectively, form an acute angle with a horizontal, and the ascending incline forms with the horizontal an angle which is greater than the acute angle.
The invention offers the particular advantage that severe injuries to human operators can be prevented by the safeguarding device according to the invention. This is achieved by providing that upon the deflection of the contact-pressure roller after a high point has been exceeded, the spring force no longer increases but instead is maintained at an allowable level. In a second exemplary embodiment, this allowed spring force is reduced even further.
In the first exemplary embodiment, the maintenance of the spring force at a predetermined level is advantageously attained by a runup incline of a control contour, which merges into a straightedge support region for one end of the shaft of the contact-pressure roller; the rectilinearly extending support region is disposed perpendicularly to the line of action of the spring force.
In a second exemplary embodiment, an advantageous feature of the invention is provided in that the runup incline merges into an oppositely oriented runout decline.
In a space-saving arrangement, a tripping mechanism is disposed in the side wall of the printing press. In this regard, the control contour having the runup incline segment is formed as a piston, which is supported displaceably in a bore of the side wall. At the same time, the piston is disposed in combination with an emergency shutoff switch.
To assure that a deflection of the contact-pressure roller over the length of the plate cylinder or the contact-pressure roller or the roller or cylinder nip defined thereby will lead to the shutoff of the printing press and, in particular, of the drive mechanism of the plate cylinder, the control contour of the axially displaceable pi
Becker Ludwig
Zuber Mathias
Gerrity Stephen F.
Greenberg Laurence A.
Heidelberger Druckmaschinen Aktiengesellschaft
Lerner Herbert J.
Stemer Werner H.
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