Printing – Flexible-sheet-securing devices
Reexamination Certificate
2000-03-27
2003-08-05
Evanisko, Leslie J. (Department: 2854)
Printing
Flexible-sheet-securing devices
C101S378000
Reexamination Certificate
active
06601508
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a device for clamping printing forms in clamping channels of reduced size.
The published European Patent Document EP 0 639 454 B1 discloses a device with a retractable hook for holding a printing plate on a support cylinder in a rotary printing press, and a rotary printing press having such a device.
The device for holding a printing plate on a support cylinder in a rotary printing press is located on a support cylinder formed with an outer surface that is cylindrical to the rotary axis of the support cylinder, and with at least one inner longitudinal bore opening out onto the outer circumferential surface via a longitudinal slot. Within the longitudinal bore, a device is provided for retaining within the slot particularly a trailing end part of the printing plate which, with respect to the support cylinder, is otherwise held by a leading edge relative to a predefined direction of rotation of the support cylinder about the rotary axis thereof, the plate in the rolled up condition thereof being clamped onto the outer circumferential surface of the support cylinder. Furthermore, a hook-forming device is formed with at least one hook extending radially outwardly in relation to the rotary axis of the support cylinder, and opposite to the direction of rotation thereof. Furthermore, a device is provided for actuating the hook-forming device, which is at least partly disposed within the bore of the support cylinder and is suitable for moving the hook reciprocatingly in a controlled manner between a forward end position relative to the direction of rotation of the support cylinder for permitting hooking or unhooking of the rear or trailing end fold of a printing form on the hook, and a rearward end position relative to the direction of rotation of the support cylinder for exerting a tensile force opposite to the direction of rotation of the support cylinder on the rear or trailing end fold of the printing form that is hooked onto the hook, the hook then being retracted into the interior of the gap or slot relative to the outer circumferential surface of the support cylinder. The hook-forming device is furthermore recessed in the gap or slot, and the hook protrudes in the forward end position thereof over the outer circumferential surface of the support cylinder. The actuating device, during the movement from the forward end position to the rearward end position, is suitable for causing the hook to withdraw into the gap or slot and, during the movement from the rearward end position to the forward end position, for causing the hook to protrude relative to the outer circumferential surface of the support cylinder. The hook-forming device includes at least one longitudinally extending sheet having a first radially inward end area relative to the rotary axis of the support cylinder, that end area being firmly connected with a clamping bar in the interior of the bore, and a second longitudinally extending end area that is located radially outside relative to the rotary axis of the support cylinder and forms the hook, and elastically deforms the sheet between the first end area and the second end area thereof.
The published European Patent Document EP 0 678 383 A1 discloses a device for changing printing forms on rotary printing presses. Both ends of a printing form are received in the cylinder gap of a printing form cylinder, the surface of the printing form being wound around the printing form cylinder. This construction provides for a device for receiving a printing form A disposed at that time on the printing form cylinder, the device having received the printing form A located at that time on the printing form cylinder after the printing form A has been released from clamping devices of the printing form cylinder, as well as a device for feeding a new printing form B, which transports a new printing form B onto the printing form cylinder. The device disclosed therein is distinguished in that, at a slight distance from the surface of the printing form cylinder, horizontally displaceable holding elements fix a leading edge of the printing form to be fed, until remotely-controlled positionable pivotable holding devices position the leading edge of the printing form to be fed onto the surface of the printing form cylinder.
The published European Patent Document EP 0 734 859 A1 is concerned with a device for changing printing forms. A pivotable printing form loading unit includes both a printing form feed and a printing form plate removal section. The printing form loading unit is pivotable both into a working position at the cylinder gap of a printing form cylinder with clamping devices and into a loading position wherein the printing form loading unit is retracted from the working position. The printing form loading unit, which is pivotable into a vertical loading position, is swivellable onto a holding element whereon a receiving area is provided for a printing form to be removed from the printing form cylinder, as well as conveyor devices for a printing form to be installed on the printing form cylinder.
The published European Patent Document EP 0 741 021 A1 discloses a device for connecting holding elements with a cross member or traverse of a printing form cylinder. This connecting device permits a flexible printing form to be fixed on the circumference of the printing form cylinder of a rotary printing press, the leading edge of the flexible printing form extending across a leading edge of a cylinder gap of the printing form cylinder, and the trailing edge of the flexible printing form being fixable by at least one flexible holding element, which is actuatably mountable on the cross member and has a hook-shaped projection on the end thereof facing towards the circumference, and is characterized in that several holding elements mountable side by side are interlockable on the cross member with locking devices. The holding elements can be inserted vertically into guides on the cross member. The device is suitable for mounting printing forms without a tool.
SUMMARY OF THE INVENTION
Starting from the foregoing state of the art, it is an object of the invention to provide a device for clamping printing forms in clamping channels of reduced size which are formed in a printing form cylinder, wherein the mounting of an endless printing form on the printing form cylinder either manually or by automatic printing form feeding devices is facilitated and improved, respectively.
With the foregoing and other objects in view, there is provided, in accordance with a first aspect of the invention, a device for holding a flexible printing form along the circumference of a printing form cylinder, so that a leading edge of the printing form engages beyond a leading edge of a clamping channel extending across the circumferential surface of the cylinder, comprising at least one resilient holding element secured to an actuatable clamp shaft for fixing a trailing edge of the flexible printing form, the holding element being a spring element that is engageable behind the trailing edge of the printing form with play when the clamp shaft is actuated.
In accordance with another feature of the invention, the holding device includes a plurality of the resilient holding elements secured to the actuatable clamp shaft for fixing the trailing edge of the flexible printing form, the plurality of holding elements being individually disposed adjacent one another and being formed as spring elements, respectively, the spring elements being engageable behind the trailing edge of the printing form with play when the clamp shaft is actuated.
In accordance with a further feature of the invention, the spring elements are supported by individual support pins in a channel formed in the clamp shaft.
In accordance with an added feature of the invention, a considerable part of the length of the spring elements protrudes above the circumferential surface of the clamp shaft.
In accordance with an additional feature of the invention, an end of the spring elemen
Evanisko Leslie J.
Heidelberger Druckmaschinen AG
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