EP0538672B1 - Web break switch for machines using webs - Google Patents

Web break switch for machines using webs Download PDF

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Publication number
EP0538672B1
EP0538672B1 EP92117079A EP92117079A EP0538672B1 EP 0538672 B1 EP0538672 B1 EP 0538672B1 EP 92117079 A EP92117079 A EP 92117079A EP 92117079 A EP92117079 A EP 92117079A EP 0538672 B1 EP0538672 B1 EP 0538672B1
Authority
EP
European Patent Office
Prior art keywords
web
gap
pressure
break detector
detector according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92117079A
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German (de)
French (fr)
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EP0538672A1 (en
Inventor
Karl Veh
Andreas Birkenfeld
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Grafotec GmbH
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Grafotec Kotterer GmbH
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Publication of EP0538672A1 publication Critical patent/EP0538672A1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H26/00—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms
    • B65H26/02—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms responsive to presence of irregularities in running webs
    • B65H26/025—Warning or safety devices, e.g. automatic fault detectors, stop-motions, for web-advancing mechanisms responsive to presence of irregularities in running webs responsive to web breakage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41F—PRINTING MACHINES OR PRESSES
    • B41F33/00—Indicating, counting, warning, control or safety devices
    • B41F33/18—Web break detection

Definitions

  • the invention relates to a web break switch for web processing machines, in particular web-fed rotary printing presses, with a monitoring device which monitors the web tension and has a pressure measuring device provided with a pressure sensor, which is assigned a gap between the web which can be acted upon by air and a stationary gap cover which is passed by the web during normal operation and generates a signal in the event of a drop in the pressure in the gap caused by a drop in the web tension.
  • a web break switch of this type is known from US-A 3 159 028.
  • a pipe connected to a compressed air source is provided, the obliquely cut end of which is placed at a clear distance above or below the web, so that there is a gap.
  • the compressed air source pressurizes this from the inside with compressed air that escapes laterally over the edge of the gap.
  • the said gap thus represents a throttle point associated with the pipeline, which is eliminated in the event of a web break. If the throttling point ceases to exist, the back pressure caused by it also ceases.
  • the pressure in the pipeline is detected by a monometer arrangement which emits a signal in the event of a pressure breakdown.
  • the gap with air entrained by the web and that the gap cover is designed as a web-parallel cover plate having at least one chamber on the web side open, from which a bore extends, to which the pressure sensor is attached.
  • the pressure built up by the air entrained by the web which is moved at high speed, or the loss of this pressure, is used to indicate a web break.
  • This not only ensures a high response speed and contactless operation, but also ensures that no individual adjustment depending on the paper quality and the like is required.
  • the measures according to the invention therefore ensure a high level of user friendliness and reliability.
  • a blowing device which can be acted upon by air can be provided with at least one nozzle opening out towards the gap.
  • a blowing device supports and improves the air supply to the gap caused by the moving web.
  • an air-inflatable blowing device with at least one nozzle opening out towards the gap can also be provided in the area of the front edge of the gap in the running direction of the web.
  • the plate forming the cover is expediently arranged above the web, so that the web automatically moves away from the plate in the event of a web break due to gravity.
  • a safety device 4 arranged upstream of the danger zone, here the dryer 3, and downstream of the printing press 2 is provided.
  • the structure and mode of operation of such safety devices are known per se and therefore require no further explanation in the present context.
  • the catching device 4 is activated by a signal generated by means of a web break switch designated as a whole by 5, as indicated by a signal flow arrow 6.
  • the web break switch 5 contains a stationary plate 7 which overlaps the paper web 1 in an edge region and which, together with the contactless one, on the lower web parallel Sheet surface 1 pasted paper web 1 limited a gap 8. Overpressure builds up in gap 8 during normal operation. In the event of a web break, the paper web 1 becomes tensionless and slack, as a result of which the gap 8 automatically increases and the excess pressure present therein collapses. This pressure change is used to activate the safety device 4.
  • a pressure sensor 9 attached to the plate 7 is provided, the measuring input 10 of which is accessible from the gap 8. With the help of the pressure sensor 9, the pressure existing in the gap 8 can accordingly be recorded.
  • the web break switch 5 contains a further pressure sensor 11 which receives the ambient pressure.
  • the outputs of the pressure sensors 9 and 11 are, as indicated by signal flow arrows 12, 13, at the inputs of a subtraction element 14 which detects the ambient pressure received by means of the pressure sensor 11 of the pressure sensor 9 subtracted gap pressure.
  • the gap pressure is greater than the ambient pressure, so that the subtraction element 14 determines a pressure difference.
  • the output of the subtraction element 14 is, as indicated by the signal arrow 15, at the input of a Switching element 16 through which the actuating device of the safety device 4 can be actuated.
  • the circuit of the switching element 16 is designed such that an activation signal is generated as soon as the difference determined by the subtraction element 14 approaches zero.
  • the activation signal generated by the switching element 16 is transmitted via the signal line 6 to the actuating device of the safety device 4.
  • the pressure sensor 11 and / or the subtraction element 14 and / or the switching element 16 can be combined in a practical embodiment with the pressure sensor 9 to form a structural unit.
  • the stationary plate 7 is carried by a bracket 17 designed as a cantilever arm and mountable on a machine side wall.
  • the plate 7 is arranged so that it is completely within the paper web 1, i.e. is laterally towered over by it. The arrangement can be made so that this is the case when processing all possible web widths.
  • the distance between the underside of the plate 7 parallel to the transport plane of the paper web 1 from the regular transport plane of the paper web 1 is small. This distance is expediently less than a millimeter.
  • the plate 7 is provided with several chambers 19, here with 9 distributed over three rows, open towards the paper web 1 and delimited by circumferential webs 18.
  • the central chamber 19 is drilled from the top of the plate.
  • the pressure sensor 9 is attached to the bore 20 provided for this purpose.
  • the Bore 20 is designed as a threaded bore into which a connecting piece containing the pressure input of the pressure sensor 9 is screwed. With the help of the pressure sensor 9, the pressure in the central chamber 19 is accordingly recorded.
  • the gap 8 and the chambers 19 communicating therewith are subjected to air by the air entrained by the paper web 1 moving at high speed in such a way that an overpressure is formed in the gap 8 and accordingly also in the chambers 19 communicating therewith.
  • these flanks can, as can best be seen from FIG. 1, be designed as phase-shaped tapered portions 21.
  • upstream and / or downstream blowing devices are provided to stabilize the gap pressure of the plate 7.
  • nozzle bars 22 which run along the rear and front edge of the plate 7 in the running direction of the paper web and are continuous across the plate width and which are provided with blowing nozzles 23 which are uniformly distributed over the plate width. These are aligned so that there is a blowing direction with a component directed into the gap 8.
  • the nozzle axis of the blowing nozzles 23 of the rear blowing device is inclined towards the rear with respect to a solder on the transport plane of the paper web 1 and the nozzle axis of the blowing nozzles 23 of the front blowing device is inclined towards the front with respect to a solder on the transport plane of the paper web 1. In the example shown, this inclination is 45 ° each.
  • the nozzle bars 22 are supplied with blown air through laterally connected compressed air lines 24.
  • the throughput volume and the pressure are chosen so that the dynamic pressure acting on the paper web 1 during normal operation is easily overcome by the web tension, so that this does not cause the paper web 1 to evade.
  • the nozzle bars 22 are designed as drilled, square cross-section rails.
  • the axial bore 25 connected to a compressed air line 24 forms a distribution chamber from which the blow nozzles 23 extend. These can simply be designed as diagonal bores, which results in a long nozzle length and thus reliable air flow.
  • the nozzle bars 22 are fastened to the plate 7 by their axial bores 25, each closing front plates 26.

Landscapes

  • Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)
  • Rotary Presses (AREA)
  • Inking, Control Or Cleaning Of Printing Machines (AREA)

Description

Die Erfindung betrifft einen Bahnreißschalter für bahnverarbeitende Maschinen, insbesondere Rollenrotationsdruckmaschinen, mit einer die Bahnspannung überwachenden Überwachungseinrichtung, die eine mit einem Druckfühler versehene Druckmesseinrichtung aufweist, die einem mit Luft beaufschlagbaren Spalt zwischen der Bahn und einer stationären, bei Normalbetrieb von der Bahn passierten Spaltabdeckung zugeordnet ist und im Falle eines durch einen Abfall der Bahnspannung bewirkten Abfalls des Drucks im Spalt ein Signal erzeugt.The invention relates to a web break switch for web processing machines, in particular web-fed rotary printing presses, with a monitoring device which monitors the web tension and has a pressure measuring device provided with a pressure sensor, which is assigned a gap between the web which can be acted upon by air and a stationary gap cover which is passed by the web during normal operation and generates a signal in the event of a drop in the pressure in the gap caused by a drop in the web tension.

Ein Bahnreißschalter dieser Art ist aus der US-A 3 159 028 bekannt. Bei dieser bekannten Anordnung ist eine an eine Druckluftquelle angeschlossene Rohrleitung vorgesehen, deren schräg abgeschnittenes Ende mit lichtem Abstand ober- oder unterhalb der Bahn platziert ist, sodaß sich ein Spalt ergibt. Dieser wird durch die Druckluftquelle von innen heraus mit Druckluft beaufschlagt, die über den Rand des Spalts seitlich entweicht. Der genannte Spalt stellt somit eine der Rohrleitung zugeordnete Drosselstelle dar, die im Falle eines Bahnbruchs wegfällt. Mit Wegfall der Drosselstelle fällt auch der durch diese bewirkte Staudruck weg. Der Druck in der Rohrleitung wird bei der bekannten Anordnung durch eine Monometeranordnung erfaßt, die im Falle eines Druckzusammenbruchs ein Signal abgibt.A web break switch of this type is known from US-A 3 159 028. In this known arrangement, a pipe connected to a compressed air source is provided, the obliquely cut end of which is placed at a clear distance above or below the web, so that there is a gap. The compressed air source pressurizes this from the inside with compressed air that escapes laterally over the edge of the gap. The said gap thus represents a throttle point associated with the pipeline, which is eliminated in the event of a web break. If the throttling point ceases to exist, the back pressure caused by it also ceases. In the known arrangement, the pressure in the pipeline is detected by a monometer arrangement which emits a signal in the event of a pressure breakdown.

Hiervon ausgehend ist es die Aufgabe der vorliegenden Erfindung, einen Bahnreißschalter eingangs erwähnter Art mit einfachen und kostengünstigen Mitteln so zu verbessern, daß eine hohe Bedienungsfreundlichkeit und Zuverlässigkeit erreicht werden.Proceeding from this, it is the object of the present invention to improve a web break switch of the type mentioned at the beginning with simple and inexpensive means in such a way that a high level of user-friendliness and reliability are achieved.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß der Spalt mit von der Bahn mitgerissener Luft beaufschlagt wird und daß die Spaltabdeckung als bahnparallele Abdeckplatte ausgebildet ist, die wenigstens eine bahnseitig offene Kammer aufweist, von der eine Bohrung abgeht, an die der Druckfühler angesetzt ist.This object is achieved in that the gap with air entrained by the web and that the gap cover is designed as a web-parallel cover plate having at least one chamber on the web side open, from which a bore extends, to which the pressure sensor is attached.

Hierbei wird der durch die von der Bahn, die mit hoher Geschwindigkeit bewegt wird, mitgerissene Luft im Spalt aufgebaute Druck, bzw. der Wegfall dieses Drucks, dazu benutzt, einen Bahnriß anzuzeigen. Dies gewährleistet nicht nur eine hohe Ansprechgeschwindigkeit und einen berührungslosen Betrieb, sondern stellt auch sicher, daß keinerlei individuelle Einstellung in Abhängigkeit von der Papierqualität und dergleichen erforderlich ist. Die erfindungsgemäßen Maßnahmen gewährleisten demnach eine hohe Bedienungsfreundlichkeit und Zuverlässigkeit.Here, the pressure built up by the air entrained by the web, which is moved at high speed, or the loss of this pressure, is used to indicate a web break. This not only ensures a high response speed and contactless operation, but also ensures that no individual adjustment depending on the paper quality and the like is required. The measures according to the invention therefore ensure a high level of user friendliness and reliability.

In zweckmäßiger Fortbildung der übergeordneten Maßnahmen kann zumindest im Bereich der in Laufrichtung der Bahn hinteren Kante des Spalts eine mit Luft beaufschlagbare Blaseinrichtung mit wenigstens einer zum Spalt hin ausmündenden Düse vorgesehen sein. Durch eine derartige Blaseinrichtung wird die durch die bewegte Bahn bewirkte Luftversorgung des Spalts unterstützt und verbessert. Um einer zu schnellen Entlüftung des Spalts entgegenzuwirken, kann in weiterer Fortbildung der übergeordneten Maßnahmen auch im Bereich der in Laufrichtung der Bahn vorderen Kante des Spalts eine mit Luft beaufschlagbare Blaseinrichtung mit wenigstens einer zum Spalt hin ausmündenden Düse vorgesehen sein.In an expedient further development of the superordinate measures, at least in the area of the rear edge of the gap in the running direction of the web, a blowing device which can be acted upon by air can be provided with at least one nozzle opening out towards the gap. Such a blowing device supports and improves the air supply to the gap caused by the moving web. In order to counteract rapid venting of the gap, in a further development of the superordinate measures, an air-inflatable blowing device with at least one nozzle opening out towards the gap can also be provided in the area of the front edge of the gap in the running direction of the web.

Zweckmäßig ist die die Abdeckung bildende Platte oberhalb der Bahn angeordnet, so daß sich die Bahn im Falle eines Bahnrisses aufgrund der Schwerkraft automatisch von der Platte entfernt.The plate forming the cover is expediently arranged above the web, so that the web automatically moves away from the plate in the event of a web break due to gravity.

Weitere vorteilhafte Ausgestaltungen und zweckmäßige Fortbildungen der übergeordneten Maßnahmen ergeben sich aus der nachstehenden Beschreibung eines Ausführungsbeispiels anhand der Zeichnung in Verbindung mit den restlichen Unteransprüchen.Further advantageous refinements and expedient further training of the higher-level measures result from the following description of an embodiment with reference to the drawing in conjunction with the remaining subclaims.

In der Zeichnung zeigen:

Figur 1
einen Längsschnitt durch einen erfindungsmäßen Bahnreißschalter mit zugeordneter Bahnfangvor richtung und
Figur 2
eine Draufsicht auf den erfindungsgemäßen Bahn reißschalter.
The drawing shows:
Figure 1
a longitudinal section through an inventive web break switch with associated Bahnfangvor direction and
Figure 2
a plan view of the web tear switch according to the invention.

Der Figur 1 liegt eine Papierbahn 1 zugrunde, die in einer Druckmaschine 2 bedruckt und anschließend in einem Trockner 3 getrocknet wird. Im Trockner 3 ist die Papierbahn 1 besonders bruchgefährdet. Um im Falle eines Bahnrisses einen Maschinenschaden in Form eines Wicklers etc. zu vermeiden, ist eine dem Gefahrenbereich, hier dem Trockner 3, vorgeordnete und der Druckmaschine 2 nachgeordnete Fangvorrichtung 4 vorgesehen. Der Aufbau und die Wirkungsweise derartiger Fangvorrichtungen sind an sich bekannt und bedürfen daher im vorliegenden Zusammenhang keiner weiteren Erläuterung mehr. Die Fangvorrichtung 4 wird durch ein mittels eines als Ganzes mit 5 bezeichneten Bahnreißschalters erzeugtes Signal aktiviert, wie durch einen Signalflußpfeil 6 angedeutet ist.1 is based on a paper web 1, which is printed in a printing press 2 and then dried in a dryer 3. In the dryer 3, the paper web 1 is particularly prone to breakage. In order to avoid machine damage in the form of a winder etc. in the event of a web break, a safety device 4 arranged upstream of the danger zone, here the dryer 3, and downstream of the printing press 2 is provided. The structure and mode of operation of such safety devices are known per se and therefore require no further explanation in the present context. The catching device 4 is activated by a signal generated by means of a web break switch designated as a whole by 5, as indicated by a signal flow arrow 6.

Der Bahnreißschalter 5 enthält eine die Papierbahn 1 in einem Randbereich übergreifende, stationäre Platte 7, die zusammen mit der berührungslos an der unteren, bahnparallelen Plattenoberfläche vorbeigeführten Papierbahn 1 einen Spalt 8 begrenzt. Im Spalt 8 baut sich während des normalen Betriebs ein Überdruck auf. Im Falle eines Bahnrisses wird die Papierbahn 1 spannungslos und schlaff, wodurch sich der Spalt 8 automatisch vergrößert und der hierin vorhandene Überdruck zusammenbricht. Diese Druckänderung wird zur Aktivierung der Fangvorrichtung 4 benutzt.The web break switch 5 contains a stationary plate 7 which overlaps the paper web 1 in an edge region and which, together with the contactless one, on the lower web parallel Sheet surface 1 pasted paper web 1 limited a gap 8. Overpressure builds up in gap 8 during normal operation. In the event of a web break, the paper web 1 becomes tensionless and slack, as a result of which the gap 8 automatically increases and the excess pressure present therein collapses. This pressure change is used to activate the safety device 4.

Hierzu ist ein an die Platte 7 angesetzter Druckfühler 9 vorgesehen, dessen Meßeingang 10 vom Spalt 8 her zugänglich ist. Mit Hilfe des Druckfühlers 9 ist demnach der im Spalt 8 vorhandene Druck aufnehmbar. Außerdem enthält der Bahnreißschalter 5 einen weiteren, den Umgebungsdruck aufnehmenden Druckfühler 11. Die Ausgänge der Druckfühler 9 und 11 liegen, wie durch Signalflußpfeile 12, 13 angedeutet ist, an den Eingängen eines Subtraktionsglieds 14, das den mittels des Druckfühlers 11 aufgenommenen Umgebungsdruck von dem mittels des Druckfühlers 9 aufgenommenen Spaltdruck subtrahiert. Während des normalen Betriebs ist der Spaltdruck größer als der Umgebungsdruck, so daß das Subtraktionsglied 14 eine Druckdifferenz ermittelt. Im Falle eines Bahnrisses entfernt sich die Papierbahn, wie oben schon erwähnt, von der Platte 7, so daß der zwischen Platte 7 und Papierbahn 1 aufgebaute Überdruck zusammenbricht und auf den Umgebungsdruck absinkt. Sobald dies der Fall ist, stellt das Subtraktionsglied 14 keine Druckdifferenz mehr fest.For this purpose, a pressure sensor 9 attached to the plate 7 is provided, the measuring input 10 of which is accessible from the gap 8. With the help of the pressure sensor 9, the pressure existing in the gap 8 can accordingly be recorded. In addition, the web break switch 5 contains a further pressure sensor 11 which receives the ambient pressure. The outputs of the pressure sensors 9 and 11 are, as indicated by signal flow arrows 12, 13, at the inputs of a subtraction element 14 which detects the ambient pressure received by means of the pressure sensor 11 of the pressure sensor 9 subtracted gap pressure. During normal operation, the gap pressure is greater than the ambient pressure, so that the subtraction element 14 determines a pressure difference. In the event of a web break, as already mentioned above, the paper web moves away from the plate 7, so that the excess pressure built up between the plate 7 and the paper web 1 breaks down and drops to the ambient pressure. As soon as this is the case, the subtraction element 14 no longer detects a pressure difference.

Der Ausgang des Subtraktionsglieds 14 liegt, wie durch den Signalpfeil 15 angedeutet ist, am Eingang eines Schaltglieds 16, durch das die Betätigungseinrichtung der Fangvorrichtung 4 betätigbar ist. Die Schaltung des Schaltglieds 16 ist dabei so ausgebildet, daß ein Aktivierungssignal erzeugt wird, sobald die vom Subtraktionsglied 14 ermittelte Differenz gegen Null geht. Das vom Schaltglied 16 erzeugte Aktivierungssignal wird über die Signalleitung 6 zur Betätigungseinrichtung der Fangvorrichtung 4 übertragen. Der Druckfühler 11 und/oder das Subtraktionsglied 14 und/oder das Schaltglied 16 können in der praktischen Ausführung mit dem Druckfühler 9 zu einer Baueinheit zusammengefaßt sein.The output of the subtraction element 14 is, as indicated by the signal arrow 15, at the input of a Switching element 16 through which the actuating device of the safety device 4 can be actuated. The circuit of the switching element 16 is designed such that an activation signal is generated as soon as the difference determined by the subtraction element 14 approaches zero. The activation signal generated by the switching element 16 is transmitted via the signal line 6 to the actuating device of the safety device 4. The pressure sensor 11 and / or the subtraction element 14 and / or the switching element 16 can be combined in a practical embodiment with the pressure sensor 9 to form a structural unit.

Die stationäre Platte 7 wird, wie Figur 2 zeigt, von einem als Kragarm ausgebildeten, an einer Maschinenseitenwand montierbaren Halter 17 getragen. Die Platte 7 ist dabei so angeordnet, daß sie sich vollständig innerhalb der Papierbahn 1 befindet, d.h. von dieser seitlich überragt wird. Die Anordnung kann dabei so getroffen werden, daß dies bei der Verarbeitung aller in Frage kommenden Bahnbreiten der Fall ist. Der Abstand der zur Transportebene der Papierbahn 1 parallelen Unterseite der Platte 7 von der regulären Transportebene der Papierbahn 1 ist gering. Zweckmäßig liegt dieser Abstand unterhalb eines Millimeters.As shown in FIG. 2, the stationary plate 7 is carried by a bracket 17 designed as a cantilever arm and mountable on a machine side wall. The plate 7 is arranged so that it is completely within the paper web 1, i.e. is laterally towered over by it. The arrangement can be made so that this is the case when processing all possible web widths. The distance between the underside of the plate 7 parallel to the transport plane of the paper web 1 from the regular transport plane of the paper web 1 is small. This distance is expediently less than a millimeter.

Die Platte 7 ist mit mehreren, hier mit 9 auf drei Reihen verteilten, zur Papierbahn 1 hin offenen, durch umlaufende Stege 18 begrenzten Kammern 19 versehen. Die zentrale Kammer 19 ist von der Plattenoberseite her angebohrt. An die hierzu vorgesehene Bohrung 20 ist der Druckfühler 9 angesetzt. Im dargestellten Ausführungsbeispiel ist die Bohrung 20 als Gewindebohrung ausgebildet, in die ein den Druckeingang des Druckfühlers 9 enthaltender Stutzen eingeschraubt ist. Mit Hilfe des Druckfühlers 9 wird demnach der Druck in der zentralen Kammer 19 aufgenommen.The plate 7 is provided with several chambers 19, here with 9 distributed over three rows, open towards the paper web 1 and delimited by circumferential webs 18. The central chamber 19 is drilled from the top of the plate. The pressure sensor 9 is attached to the bore 20 provided for this purpose. In the illustrated embodiment, the Bore 20 is designed as a threaded bore into which a connecting piece containing the pressure input of the pressure sensor 9 is screwed. With the help of the pressure sensor 9, the pressure in the central chamber 19 is accordingly recorded.

Der Spalt 8 und die hiermit kommunizierenden Kammern 19 werden durch die von der mit hoher Geschwindigkeit bewegten Papierbahn 1 mitgerissene Luft so mit Luft beaufschlagt, daß sich im Spalt 8 und dementsprechend auch in den hiermit kommunizierenden Kammern 19 ein Überdruck ausbildet. Um einer Wirbelbildung im Bereich der quer zur Bahnlaufrichtung verlaufenden Flanken der Platte 7 entgegenzuwirken können diese Flanken, wie am besten aus Figur 1 erkennbar ist, als phasenförmige Verjüngungen 21 ausgebildet sein. Im dargestellten Beispiel sind zur Stabilisierung des Spaltdrucks der Platte 7 vor- und/oder nachgeordnete Blaseinrichtungen vorgesehen. Diese sind als entlang der in Laufrichtung der Papierbahn hinteren und vorderen Kante der Platte 7 verlaufende, über die Plattenbreite durchgehende Düsenbalken 22 ausgebildet, die mit über die Plattenbreite gleichmäßig verteilten Blasdüsen 23 versehen sind. Diese sind so ausgerichtet, daß sich eine Blasrichtung mit einer in den Spalt 8 hineingerichteten Komponente ergibt. Hierzu ist die Düsenachse der Blasdüsen 23 der hinteren Blaseinrichtung gegenüber einem Lot auf die Transportebene der Papierbahn 1 nach hinten und die Düsenachse der Blasdüsen 23 der vorderen Blaseinrichtung gegenüber einem Lot auf die Transportebene der Papierbahn 1 nach vorne geneigt. Im dargestellten Beispiel beträgt diese Neigung jeweils 45°.The gap 8 and the chambers 19 communicating therewith are subjected to air by the air entrained by the paper web 1 moving at high speed in such a way that an overpressure is formed in the gap 8 and accordingly also in the chambers 19 communicating therewith. In order to counteract the formation of eddies in the region of the flanks of the plate 7 which run transversely to the web running direction, these flanks can, as can best be seen from FIG. 1, be designed as phase-shaped tapered portions 21. In the example shown, upstream and / or downstream blowing devices are provided to stabilize the gap pressure of the plate 7. These are designed as nozzle bars 22 which run along the rear and front edge of the plate 7 in the running direction of the paper web and are continuous across the plate width and which are provided with blowing nozzles 23 which are uniformly distributed over the plate width. These are aligned so that there is a blowing direction with a component directed into the gap 8. For this purpose, the nozzle axis of the blowing nozzles 23 of the rear blowing device is inclined towards the rear with respect to a solder on the transport plane of the paper web 1 and the nozzle axis of the blowing nozzles 23 of the front blowing device is inclined towards the front with respect to a solder on the transport plane of the paper web 1. In the example shown, this inclination is 45 ° each.

Die Düsenbalken 22 werden, wie Figur 2 weiter zeigt, durch seitlich angeschlossene Druckluftleitungen 24 mit Blasluft versorgt. Das Durchsatzvolumen und der Druck sind dabei so gewählt, daß der bei Normalbetrieb auf die Papierbahn 1 wirkende Staudruck ohne weiteres vom Bahnzug überwunden wird, so daß hierdurch kein Ausweichen der Papierbahn 1 bewirkt wird. Die Düsenbalken 22 sind im dargestellten Beispiel als aufgebohrte, quadratischen Querschnitt aufweisende Schienen ausgebildet. Die axiale, an eine Druckluftleitung 24 angeschlossene Bohrung 25 bildet dabei eine Verteilerkammer, von der die Blasdüsen 23 abgehen. Diese können einfach als Diagonalbohrungen ausgebildet sein, wodurch sich eine große Düsenlänge und damit eine zuverlässige Luftführung ergibt. Die Düsenbalken 22 sind durch ihre Axialbohrung 25 jeweils verschließende, stirnseitige Laschen 26 an der Platte 7 befestigt.As further shown in FIG. 2, the nozzle bars 22 are supplied with blown air through laterally connected compressed air lines 24. The throughput volume and the pressure are chosen so that the dynamic pressure acting on the paper web 1 during normal operation is easily overcome by the web tension, so that this does not cause the paper web 1 to evade. In the example shown, the nozzle bars 22 are designed as drilled, square cross-section rails. The axial bore 25 connected to a compressed air line 24 forms a distribution chamber from which the blow nozzles 23 extend. These can simply be designed as diagonal bores, which results in a long nozzle length and thus reliable air flow. The nozzle bars 22 are fastened to the plate 7 by their axial bores 25, each closing front plates 26.

Claims (8)

  1. Web break detector for web-processing machines, in particular web-fed rotary presses, with a monitoring device monitoring web tension which has a pressure measuring unit provided with a pressure sensor (9) and assigned to a gap (8) to which air can be admitted, between the web (1) and a stationary gap cover passed by the web (1) in normal operation, and which in the case of a drop in pressure in the gap (8) due to a loss of web tension generates a signal, characterized in that the gap is supplied with air dragged along by the web (1) and that the gap cover is in the form of a cover plate parallel to the web, with at least one chamber (19) open on the web side, from which extends a bore (20) on which the pressure sensor (9) is placed.
  2. Web break detector according to claim 1, characterized in that the monitoring device is in the form of a differential pressure measuring device, which has a pressure sensor (9) recording the gap pressure and a pressure sensor (11) recording the ambient pressure, and which generates a signal if the gap pressure approaches the ambient pressure, preferably with elimination of the pressure difference.
  3. Web break detector according to any of the preceding claims, characterized in that the plate (7) has several chambers (19) and that the centrally-located chamber (19) can be scanned by means of the assigned pressure sensor (9).
  4. Web break detector according to any of the preceding claims, characterized in that, in the area of the rear edge of the gap (8) in the direction of movement of the web (1), a blower which can be supplied with air, with one or more nozzles (23) discharging towards the gap (8), is provided.
  5. Web break detector according to any of the preceding claims, characterized in that, in the area of the leading edge of the gap (8) in the direction of movement of the web (1), a blower which can be supplied with air, with one or more nozzles (23) discharging towards the gap (8), is provided.
  6. Web break detector according to claims 4 or 5, characterized in that the blower(s) located before and/or after the gap (8) is/are in the form of nozzle bars (22) continuous over the width of the plate (7).
  7. Web break detector according to any of the preceding claims, characterized in that the plate is tapered in the area of its front and rear flanks.
  8. Web break detector according to any of the preceding claims, characterized in that the plate (7) is mounted above the web (1).
EP92117079A 1991-10-19 1992-10-07 Web break switch for machines using webs Expired - Lifetime EP0538672B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4134590 1991-10-19
DE4134590A DE4134590C2 (en) 1991-10-19 1991-10-19 Device for monitoring web processing in a web-fed rotary printing press

Publications (2)

Publication Number Publication Date
EP0538672A1 EP0538672A1 (en) 1993-04-28
EP0538672B1 true EP0538672B1 (en) 1996-04-24

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EP92117079A Expired - Lifetime EP0538672B1 (en) 1991-10-19 1992-10-07 Web break switch for machines using webs

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US (1) US5301866A (en)
EP (1) EP0538672B1 (en)
JP (1) JP3245751B2 (en)
DE (2) DE4134590C2 (en)

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Also Published As

Publication number Publication date
EP0538672A1 (en) 1993-04-28
JP3245751B2 (en) 2002-01-15
JPH05215669A (en) 1993-08-24
DE59206107D1 (en) 1996-05-30
DE4134590C2 (en) 1996-02-15
US5301866A (en) 1994-04-12
DE4134590A1 (en) 1993-04-22

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