Printing – Rolling contact machines – Rotary
Reexamination Certificate
2002-09-25
2004-07-13
Nguyen, Anthony H. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S219000
Reexamination Certificate
active
06761111
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a catching device for a torn transport belt in a folder of a printing press and to a folder having a catching device.
A catching device of this general type is disclosed in German Published, Non-Prosecuted Patent Application DE 101 06 945 A1. As described therein, the catching device includes a holding device for a transport belt, which has two catching elements between which the transport belt runs and which can hold the latter firmly therebetween, a surface of a first one of the catching elements facing towards the transport belt being convex. The catching device also includes a measuring device for measuring tension of the transport belt, which is constructed so that when the tension falls below a prescribed value, the holding device is triggered.
The transport belt can be part of a transport device for flat products, whether they are signatures or a printing material web, such as for printed copies which are processed in a folder disposed downstream from a planographic printing press or a rotary printing press, in particular a web-fed rotary printing press. In this regard, the transport device can comprise a plurality of such transport belts formed as an endless belt, which are disposed side-by-side and together form the transport surface. However, it can also comprise a single, long endless belt which is guided in such a manner that it forms a plurality of individual strands, respectively, representing one transport belt, the individual strands being disposed beside one another and together forming the transport surface.
In the heretofore-known catching device, the first catching element is a catching roller having a circumferential surface forming the convex surface facing the transport belt. The catching roller is pressed against the transport belt by a pretensioning element and, due to the tension prevailing in the transport belt, is kept at a distance from the second catching element which, in the case of the heretoforeknown catching device, is formed by a locally fixed stop element. This stop element is formed as a round rod which extends transversely to the revolving direction of the transport belt, so that the surface of the second catching element facing the transport belt is also convex.
If the transport belt should then tear upstream of the catching device, as viewed in the revolving direction, the tension of the transport belt collapses thereat and is therefore no longer sufficient to keep the pretensioned catching roller at a distance from the stop element. The catching roller is therefore moved towards the stop element by the pretensioning element and pressed against the stop element, so that the transport belt is clamped therebetween and firmly held. The pretensioning element can therefore be viewed as a measuring device for the tension of the transport belt, because it triggers the holding device when the tension falls below the prescibed value.
One disadvantage of this heretofore-known catching device is that the catching roller and the stop element rest only on a very narrow strip of the transport belt with the convex surfaces thereof facing towards the transport belt, and therefore cannot hold the transport belt sufficiently firmly.
Published European Patent Application EP 0 318 853 A, corresponding to U.S. Pat. No. 4,887,532, discloses a catching device for a torn paper web in a web-fed rotary printing press. Disposed downstream from a printing unit is a clamping and/or severing device for the web, which is formed with a passage slot and is actuatable by a web scanning device that detects a web break. The clamping and/or severing device has clamping jaws and/or knock-off knives which are movable towards one another. However, the precise form of two cooperating clamping jaws cannot be determined from this document.
Published European Patent Application EP 0 476 437 A, corresponding to U.S. Pat. No. 5,163,371, discloses a catching device for a torn printing material web in a web-fed rotary printing press. This heretofore-known catching device has a clamping device disposed downstream from a printing unit and a web break switch. The clamping device comprises a driven roller and a rotor movable by a setting or adjusting device, the printing material web running between the roller and the rotor. The setting device is activatable by the web break switch and then moves the rotor into contact with the roller.
In this heretofore-known catching device, too, the surfaces of the roller and the rotor which face the printing material web are convex.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a catching device for a torn transport belt in a folder of a printing press and a folder having a catching device, which can hold the transport belt more firmly than the heretofore-known catching devices and folders of this general type.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a device for catching a torn transport belt. The catching device comprises a holding device for the transport belt, which has two catching elements between which the transport belt runs, the catching elements serving for holding the transport belt firmly therebetween. A first one of the two catching elements has a convex surface facing towards the transport belt, and the second one of the two catching elements has a concave surface facing towards the transport belt. Also provided is a device for measuring tension of the transport belt, the tension measuring device being constructed for triggering the holding device when the tension of the transport belt falls below a prescribed value.
In accordance with another feature of the invention, the first catching element is a roller and the second catching element is a channel, the roller having a rotational axis extending at least approximately parallel to a longitudinal axis of the channel.
In accordance with a further feature of the invention, the channel has a V-shaped cross section.
In accordance with an added feature of the invention, the channel has a circular cross section with an inner diameter at least equal to the diameter of the roller.
In accordance with an additional feature of the invention, in order to hold the transport belt firmly, at least one of the first and the second catching elements is movable towards the respective other of the first and the second catching elements.
In accordance with yet another feature of the invention, the roller is pretensioned against the transport belt.
In accordance with yet a further feature of the invention, the measuring device comprises a pull cylinder having a piston rod to which the roller is affixed, and a housing to which the channel is affixed.
In accordance with yet an added feature of the invention, the measuring device has an end position transmitter disposed at an end of the cylinder housing distal from the channel.
In accordance with yet an additional feature of the invention, the measuring device is constructed for registering a change in speed of a section of the transport belt.
In accordance with still another feature of the invention, the measuring device is constructed for registering speeds of two different sections of the transport belt.
In accordance with still a further feature of the invention, the catching device further comprises at least one further holding device disposed at another location of the transport belt and connected to the measuring device.
In accordance with still an added feature of the invention, the further holding device comprises a clamping block formed with a guide groove wherein the transport belt runs, and a clamping jaw pressed against the base of the guide groove for firmly holding the transport belt.
In accordance with a concomitant aspect of the invention, there is provided a folder disposed downstream of a printing press, as viewed in travel direction of a printing product. The folder includes a device for catching a torn transport belt, which comprises a holding device for the tr
Chagnon Franck
Robert Jean-Francois
Robin Philippe
Greenberg Laurence A.
Heidelberger Druckmaschinen AG
Mayback Gregory L.
Nguyen Anthony H.
Stemer Werner H.
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