Sheet feeding or delivering – Delivering – By pneumatic conveyor
Patent
1996-08-30
1998-09-08
Bollinger, David H.
Sheet feeding or delivering
Delivering
By pneumatic conveyor
B65H 2924
Patent
active
058034480
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a device for the suspended guidance of sheets or webs in processing machines, in particular rotary printing presses.
DESCRIPTION OF THE PRIOR ART
DE-PS 19 07 083 describes a blowing chamber with several blower openings disposed in a distributed manner, which openings respectively have an oblique guide surface extending downward into the blowing chamber. However, in this case, the nozzles have a tongue and the radial guide surfaces enclose an angle between 120.degree. and 180.degree.. By means of this, a widely fanned out jet with a flat effect is generated, not a directed jet. Also, all blowing nozzles are disposed in the same direction. By means of this, it is possible to exert a barely tightening force in only one direction, which is particularly disadvantageous with thin sheets, because they easily tend to flutter because of this.
DE-PS 28 02 610 discloses nozzles, the lateral surfaces of whose oblique guide surfaces extend parallel and are provided with a lowered tongue. These nozzles are disposed closely together next to each other on blowing chambers. A guide path is described, which consists of several blowing chambers which are disposed above and below of sheets to be guided. No closed guide surface results from this. The air flows off through gaps created between the individual blowing chambers, so that no even air cushion is created and the sheets are guided along the guide path in a wave shape. It is disadvantageous in connection with the described nozzles that the emerging air jets do no diverge, so that a large number of nozzles are required for building a homogeneous air cushion.
A device in accordance with the species for the suspended guidance of sheets or webs in processing machines is known from DE 89 15 626 U1. Here, the blowing jets extend in the center of the device approximately parallel with the direction of conveyance, and in the adjoining areas extend away in steps from the conveying device.
With this device it is disadvantageous that the blowing jets of this device cause thin sheets in particular to begin fluttering.
SUMMARY OF THE INVENTION
It is the object of the invention to create a device by means of which sheets or webs are guided contactless and are tightened in the direction of free edges through a processing machine, preferably a rotary printing press, without blowing jets being generated which tend to form waves, i.e. which tend to create fluttering.
This object is attained in accordance with the invention by means of a device which is provided with a plurality of nozzles that are inserted into an otherwise closed sheet guidance surface that is facing the sheets or web being guided. The nozzles are arranged to divide the guidance surface into at least three zones across its width. These zones are a central stabilizing zone and two tightening zones. The nozzles in the two tightening zones direct air flow out from an axis of symmetry and generally in a direction opposite to the sheet or web conveying direction.
It is achieved by means of the nozzles in accordance with the invention, and their arrangement, that a particularly even air cushion is formed over an entire guidance surface. By means of this air cushion, a sheet or a web is simultaneously supported and aspirated because of the effect of the aerodynamic paradox. In spite of this even air cushion, in which the suction and pressure forces are in an equilibrium, directed, slightly diverging flows of the nozzles exert forces for tightening in defined directions. In an advantageous manner these forces are directed to free edges of the sheet.
A division of the guidance surface into three zones across its width, a central stabilization zone, and right and left tightening zones has been shown to be particularly advantageous.
An even air cushion is generated in this area of the guidance surface by means of the stabilization zone located symmetrically with an axis of symmetry, which simultaneously exerts a tightening effect on the sheet opposite the conveying dir
REFERENCES:
patent: 3633281 (1972-01-01), Vits
patent: 4197621 (1980-04-01), Mair
patent: 4218001 (1980-08-01), Vits
patent: 5102118 (1992-04-01), Vits
patent: 5687964 (1997-11-01), Stephan et al.
Schwitzky Volkmar Rolf
Stiel Jurgen Alfred
Bollinger David H.
Koenig & Bauer--Albert Aktiengesellschaft
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