EP0355520A2 - Method of heat treating workpieces - Google Patents

Method of heat treating workpieces Download PDF

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Publication number
EP0355520A2
EP0355520A2 EP89114350A EP89114350A EP0355520A2 EP 0355520 A2 EP0355520 A2 EP 0355520A2 EP 89114350 A EP89114350 A EP 89114350A EP 89114350 A EP89114350 A EP 89114350A EP 0355520 A2 EP0355520 A2 EP 0355520A2
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EP
European Patent Office
Prior art keywords
furnace
treatment
flow
treatment gas
gas
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.)
Granted
Application number
EP89114350A
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German (de)
French (fr)
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EP0355520A3 (en
EP0355520B1 (en
Inventor
Peter Dr. Dipl.-Ing. Vocke
Thomas Dipl.-Ing. Kamm
Andreas Dipl.-Ing. Dey
Hilmar Dipl.-Ing. Storz
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Linde GmbH
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Linde GmbH
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Priority to AT89114350T priority Critical patent/ATE104360T1/en
Publication of EP0355520A2 publication Critical patent/EP0355520A2/en
Publication of EP0355520A3 publication Critical patent/EP0355520A3/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0056—Furnaces through which the charge is moved in a horizontal straight path
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B9/3005—Details, accessories, or equipment peculiar to furnaces of these types arrangements for circulating gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F27D7/02—Supplying steam, vapour, gases, or liquids

Definitions

  • the invention relates to a method for the heat treatment of workpieces in a treatment gas atmosphere in a continuous furnace with an inlet, treatment and cooling zone.
  • heat treatment processes for metallic workpieces under a wide variety of treatment gas atmospheres are known.
  • these are carburizing, hardening, nitriding and annealing processes e.g. among endogas, exogas, methanol and ammonia cracked gas and gases that are delivered ready to use and can be removed from storage tanks (e.g. nitrogen, hydrogen).
  • Heat treatment methods under treatment gas for ceramic workpieces in continuous furnaces are also known, e.g. the burning of such workpieces.
  • the treatment gas atmospheres can be divided into protective gas atmospheres and reaction gas atmospheres. Shielding gases have the task of to protect the treating materials during heat treatment from undesired influences, for example from reactions with the oxygen, carbon dioxide or water vapor contained in the air, while desired reactions with the material to be treated are brought about in reaction gas atmospheres.
  • the treatment gases are generally introduced into the heat treatment devices or furnaces at a number of points with a pressure slightly above atmospheric pressure (approximately between 0.01 and 0.2 mbar) and a low flow rate.
  • the feed quantities and the feed points are selected so that a treatment gas atmosphere which is of sufficient quality for the respective treatment is established throughout the device and leak losses are compensated for.
  • there is no deliberately chosen preferred flow direction of the introduced treatment gas but rather a flow depends on the particular furnace design, the flow essentially from one or more feed points to one or more main outflow points, e.g. the furnace entrance and exit.
  • a heat treatment method for a continuous furnace is known from EP-B1 75 438, for example, in which a flow in the direction of the furnace entrance is brought about essentially by a curtain-like separation at the furnace exit and a suitable introduction rate of the treatment gas into the different furnace regions. As a result, the total amount of treatment gas required for a heat treatment is reduced.
  • a blowing device particularly suitable for carrying out the invention essentially consists of a straight, elongated tube, one end of which is closed except for one or more gas outlet openings with the desired orientation and which can be connected to a treatment gas supply via the other end.
  • a straight, elongated tube in contrast to curved or diameter-varying shapes, can simply be inserted into an opening in the furnace wall and installed therein.
  • the tubular injection device is designed to be rotatable about its longitudinal axis at least by 180 ° at least in the region of the gas outlet opening (s).
  • part of the treatment gas is blown into the cooling zone of the furnace system with the aid of blowing device 7.
  • the blowing device 7 is arranged approximately in the central part of the cooling zone 4 and, in the case shown, is aligned against the direction of flow of the objects to be treated.
  • Treatment gas is also fed on both sides of the blowing device 7 with supply lines 13, 14 to the cooling zone. Due to the directed blowing at high pressure, i.e. pressure between 1 and 20 bar, preferably between 2 and 6 bar, the gas surrounding the blowing nozzle is entrained and so there is initially a flow in the cooling zone which flows to the treatment zone 3, whereby on Oven exit 6 even a small proportion of the outside air is sucked in.
  • this flow orientation results in a type of stowage area, in which treatment gas flowing out of the treatment zone and flowing with the flow from the cooling zone 4 runs against one another. Overall, this essentially prevents treatment gas from flowing out of the treatment zone into the cooling zone. The result of this is that excess treatment gas flows out of the treatment zone 3 essentially towards the inlet zone 2, which in turn creates a gas flow there opposite to the direction of flow towards the furnace inlet 5.
  • a furnace gas flow similar to that described below in connection with FIG. 2, can be generated in the direction of flow of the objects to be treated.
  • FIG. 2 shows a continuous furnace 1 with two blowing devices 7, 8 which can be switched alternately via the three-way valve 10 and only one further feed line 14 for treatment gas into the cooling zone 4. If the blowing device 7 is switched, a furnace gas flow against the direction of flow is generated in a manner similar to that just described. If a furnace train is to be produced in the direction of flow, treatment gas 8 is blown in the direction of the furnace exit into the cooling zone with the blowing device 8 arranged in the first third of the cooling zone 4 following the treatment zone 3, which in turn acts upon the entire atmosphere in the cooling zone with this flow direction and in addition - with this arrangement of the injection nozzle 8 - treatment gas is already sucked out of the treatment zone 3.
  • the aim with regard to heat treatments under treatment gas is the inevitable intrusion of air components into the furnace - which is known to be reduced by a high throughput of treatment gas through the furnace - intentionally allowed on one side on the side that is harmless to the heat treatment material. This is achieved through the directional flow.
  • significant savings in treatment gas are possible compared to the conventional process, since the furnace atmosphere can still be produced in all furnace areas with the necessary purity using a smaller amount of gas. This is an essential effect of the method according to the invention.
  • the amount of the injected treatment gas is between 3 and 35%, preferably between 5 and 20%, of the amount that is supplied to the heat treatment device in a conventional manner.
  • An example of a treatment in which the method according to the invention can be used with a furnace train directed against the direction of flow is the annealing of nickel-copper alloys, since the penetration of air, especially oxygen, into the materials due to the high corrosion resistance of these materials the cooling zone does not deteriorate the annealing result.
  • the annealing of steel should be mentioned, in which it is possible to work with a furnace train directed in the direction of passage, since a certain degree of contamination from the air, in particular based on carbon dioxide, is tolerable for steel in the entrance area of the treatment furnace.
  • the method according to the invention can also be used to influence a flow occurring from the beginning in a treatment furnace.
  • a flow occurring from the beginning in a treatment furnace For example, in an oven system due to unfavorable drafts in the hall surrounding the oven system, the use of the method according to the invention, even in a controlled version with an oven draft sensor and a correspondingly adjustable injection pressure, is a suitable way of generating a desired oven draft.
  • the method according to the invention can be used in many heat treatments in an economically and / or technically advantageous manner.

Abstract

The invention relates to a method of heat treating workpieces (metal, ceramic) in a continuous furnace and, at the same time, especially to the influencing of the flow of the treatment-gas atmosphere existing in the furnace. It is possible to influence the flow of the furnace gas by blowing in a proportion of the treatment gas required for the heat treatment at a pressure lying above the normal feed pressure of the treatment gas and directed into one or more furnace zones.

Description

Die Erfindung bezieht sich auf ein Verfahren zur Wärme­behandlung von Werkstücken in einer Behandlungsgas­atmosphäre in einem Durchlaufofen mit Einlauf-, Behandlungs- und Kühlzone.The invention relates to a method for the heat treatment of workpieces in a treatment gas atmosphere in a continuous furnace with an inlet, treatment and cooling zone.

Es sind beispielsweise vielerlei Wärmebehandlungs­verfahren für metallische Werkstücke unter verschiedensten Behandlungsgasatmosphären bekannt. Beispiele hierfür sind Aufkohl-, Härte-, Nitrier- und Glühverfahren z.B. unter Endogas, Exogas, Methanol- und Ammoniakspaltgas und Gasen, die verbrauchsfertig geliefert aus Speicherbehältern entnehmbar sind (z.B. Stickstoff, Wasserstoff). Ebenso sind Wärmebehandlungsverfahren unter Behandlungsgas für keramische Werkstücke in Durchlauföfen bekannt, z.B. das Brennen derartiger Werkstücke.For example, a wide variety of heat treatment processes for metallic workpieces under a wide variety of treatment gas atmospheres are known. Examples of these are carburizing, hardening, nitriding and annealing processes e.g. among endogas, exogas, methanol and ammonia cracked gas and gases that are delivered ready to use and can be removed from storage tanks (e.g. nitrogen, hydrogen). Heat treatment methods under treatment gas for ceramic workpieces in continuous furnaces are also known, e.g. the burning of such workpieces.

Die Behandlungsgasatmosphären lassen sich dabei in Schutzgasatmosphären und Reaktionsgasatmosphären einteilen. Schutzgase haben die Aufgabe, die zu behandelnden Werkstoffe bei der Wärmebehandlung vor unerwünschten Einflüssen zu schützen, z.B. vor Reaktionen mit dem in der Luft enthaltenen Sauerstoff, Kohlendioxid oder Wasserdampf, während mit Reaktions- gasatmosphären gewünschte Reaktionen mit dem zu behandelnden Werkstoff herbeigeführt werden.The treatment gas atmospheres can be divided into protective gas atmospheres and reaction gas atmospheres. Shielding gases have the task of to protect the treating materials during heat treatment from undesired influences, for example from reactions with the oxygen, carbon dioxide or water vapor contained in the air, while desired reactions with the material to be treated are brought about in reaction gas atmospheres.

Die Behandlungsgase werden bei den heute bekannten Verfahren in der Regel an mehreren Stellen mit geringfügig über dem Atmosphärendruck liegenden Druck (etwa zwischen 0.01 und 0.2 mbar) und niedriger Strömungsgeschwindigkeit in die Wärmebehandlungs­einrichtungen bzw -öfen eingeführt. Dabei werden die Einspeisemengen und die Einspeisestellen so gewählt, daß sich überall in der Einrichtung eine qualitativ für die jeweilige Behandlung ausreichende Behandlungsgas­atmosphäre einstellt und Leckverluste ausgeglichen werden. Im Regelfall besteht dabei keine absichtlich gewählte Vorzugsstromrichtung des eingeleiteten Behandlungsgases, sondern es ergibt sich ein Strom, der von der jeweiligen Ofenausgestaltung abhängt, wobei der Strom im wesentlichen von einer oder mehreren Einspeisestellen zu einer oder mehreren Hauptausfluß­stellen, z.B. dem Ofenein- und -ausgang, verläuft.In the processes known today, the treatment gases are generally introduced into the heat treatment devices or furnaces at a number of points with a pressure slightly above atmospheric pressure (approximately between 0.01 and 0.2 mbar) and a low flow rate. The feed quantities and the feed points are selected so that a treatment gas atmosphere which is of sufficient quality for the respective treatment is established throughout the device and leak losses are compensated for. As a rule, there is no deliberately chosen preferred flow direction of the introduced treatment gas, but rather a flow depends on the particular furnace design, the flow essentially from one or more feed points to one or more main outflow points, e.g. the furnace entrance and exit.

Andererseits ist z.B. aus der EP-B1 75 438 ein Wärmebehandlungsverfahren für einen Durchlaufofen bekannt, bei dem im wesentlichen durch eine vorhangartige Abtrennung am Ofenausgang und eine geeignete Einführungsrate des Behandlungsgases in die verschiedenen Ofenbereiche eine Strömung in Richtung des Ofeneingangs bewirkt wird. Dadurch wird die Gesamtmenge an notwendigem Behandlungsgas für eine Wärmebehandlung reduziert.







On the other hand, a heat treatment method for a continuous furnace is known from EP-B1 75 438, for example, in which a flow in the direction of the furnace entrance is brought about essentially by a curtain-like separation at the furnace exit and a suitable introduction rate of the treatment gas into the different furnace regions. As a result, the total amount of treatment gas required for a heat treatment is reduced.







Eine zur Ausführung der Erfindung besonders geeignete Einblasvorrichtung besteht im wesentlichen aus einer geraden, länglichen Röhre, deren eines Ende bis auf eine oder mehrere Gasauslaßöffnungen mit gewünschter Ausrichtung verschlossen ist und die über das andere Ende mit einer Behandlungsgasversorgung verbindbar ist.A blowing device particularly suitable for carrying out the invention essentially consists of a straight, elongated tube, one end of which is closed except for one or more gas outlet openings with the desired orientation and which can be connected to a treatment gas supply via the other end.

Eine gerade, längliche Röhre kann im Gegensatz zu krummen oder im Durchmesser variierenden Formen einfach in eine in der Ofenwand angebrachte Öffnung eingeführt und darin montiert werden.A straight, elongated tube, in contrast to curved or diameter-varying shapes, can simply be inserted into an opening in the furnace wall and installed therein.

In einer vorteilhaften Ausgestaltung ist die rohrartige Einblasvorrichtung zumindest im Bereich der Gasauslaßöffnung(en) um ihre Längsachse mindestens um 180 ° drehbar ausgestaltet. Dadurch kann mit einer Einblasvorrichtung eine Strömung in oder eine Strömung gegen die Durchlaufrichtung in einem Durchlaufofen erzeugt werden.In an advantageous embodiment, the tubular injection device is designed to be rotatable about its longitudinal axis at least by 180 ° at least in the region of the gas outlet opening (s). As a result, a flow into or a flow against the direction of flow can be generated in a continuous furnace with a blowing device.

Anhand der folgenden schematischen Zeichnungen soll das erfindungsgemäße Verfahren mit dazugehörigen Vorrichtungen beispielhaft näher erläutert und eine erf indungsgemäße Einblasvorrichtung genauer beschrieben werden.On the basis of the following schematic drawings, the method according to the invention with associated devices will be explained in more detail by way of example and a blowing device according to the invention will be described in more detail.

Es zeigen:

  • Figur 1 einen Durchlaufofen mit einer in der Kühlzone angebrachten Einblasvorrichtung,
  • Figur 2 einen Durchlaufofen mit zwei Einblasvorrich­tungen in der Kühlzone,
  • Figur 3 eine Einblasvorrichtung .




Show it:
  • FIG. 1 shows a continuous furnace with a blowing device installed in the cooling zone,
  • FIG. 2 shows a continuous furnace with two blowing devices in the cooling zone,
  • Figure 3 shows a blowing device.




Erfindungsgemäß dagegen, wird, wie beispielsweise in Figur 1 gezeigt, ein Teil des Behandlungsgases mit Hilfe von Einblasvorrichtung 7 in die Kühlzone der Ofenanlage gerichtet eingeblasen. Die Einblasvorrichtung 7 ist etwa im mittleren Teil der Kühlzone 4 angeordnet und im gezeichneten Fall gegen die Durchlaufrichtung der zu behandelnden Gegenstände ausgerichtet. Behandlungsgas wird außerdem beidseitig der Einblasvorrichtung 7 mit Zufuhrleitungen 13, 14 der Kühlzone zugeführt. Durch das gerichtete Einblasen mit hohem Druck, also Drucken zwischen 1 und 20 bar, vorzugsweise zwischen 2 und 6 bar, wird das die Einblasdüse umgebende Gas mitgerissen und es ergibt sich so zunächst in der Kühlzone eine Strömung die zur Behandlungszone 3 hin fließt, wobei am Ofenausgang 6 sogar ein geringer Anteil der außen anliegenden Luft eingesaugt wird. Zur Behandlungszone hin ergibt sich durch diese Strömungsausrichtung eine Art Staubereich, in dem aus der Behandlungszone ausfließendes und mit der Strömung aus der Kühlzone 4 fließendes Behandlungsgas gegeneinander anlaufen. Ingesamt wird dadurch im wesentlichen ein Ausfließen von Behandlungsgas aus der Behandlungszone in die Kühlzone verhindert. Dies hat zur Folge, daß Überschußbehandlungsgas aus der Behandlungszone 3 im wesentlichen zur Einlaufzone 2 hin abfließt, wodurch dort wiederum eine Gasströmung entgegengesetzt zur Durchlaufrichtung hin zum Ofeneingang 5 entsteht. Diese Strömungsverhältnisse sind durch die in Figur 1 dargestellten Pfeile angedeutet.In contrast, according to the invention, as shown in FIG. 1, for example, part of the treatment gas is blown into the cooling zone of the furnace system with the aid of blowing device 7. The blowing device 7 is arranged approximately in the central part of the cooling zone 4 and, in the case shown, is aligned against the direction of flow of the objects to be treated. Treatment gas is also fed on both sides of the blowing device 7 with supply lines 13, 14 to the cooling zone. Due to the directed blowing at high pressure, i.e. pressure between 1 and 20 bar, preferably between 2 and 6 bar, the gas surrounding the blowing nozzle is entrained and so there is initially a flow in the cooling zone which flows to the treatment zone 3, whereby on Oven exit 6 even a small proportion of the outside air is sucked in. Towards the treatment zone, this flow orientation results in a type of stowage area, in which treatment gas flowing out of the treatment zone and flowing with the flow from the cooling zone 4 runs against one another. Overall, this essentially prevents treatment gas from flowing out of the treatment zone into the cooling zone. The result of this is that excess treatment gas flows out of the treatment zone 3 essentially towards the inlet zone 2, which in turn creates a gas flow there opposite to the direction of flow towards the furnace inlet 5. These flow conditions are indicated by the arrows shown in Figure 1.

Durch drehen der Einblasvorrichtung um 180 ° kann dagegen eine Ofengasströmung, ähnlich wie im folgenden in Zusammenhang mit Figur 2 beschrieben, in Durchlaufrichtung der zu behandelnden Gegenstände erzeugt werden.By rotating the blowing device through 180 °, on the other hand, a furnace gas flow, similar to that described below in connection with FIG. 2, can be generated in the direction of flow of the objects to be treated.

In Figur 2 ist ein Durchlaufofen 1 mit zwei über das Dreiwegeventil 10 wechselweise schaltbaren Einblasvorrichtungen 7, 8 und nur einer weiteren Zufuhrleitung 14 für Behandlungsgas in die Kühlzone 4 dargestellt. Ist die Einblasvorrichtung 7 geschaltet wird eine Ofengasströmung gegen die Durchlaufrichtung ähnlich wie eben beschrieben erzeugt. Soll ein Ofenzug in Durchlaufrichtung erzeugt werden, wird mit der im ersten Drittel der Kühlzone 4 im Anschluß an die Behandlungszone 3 angeordneten Einblasvorrichtung 8 Behandlungsgas in Richtung des Ofenausganges in die Kühlzone eingeblasen, wodurch wiederum die gesamte Atmosphäre in der Kühlzone mit dieser Strömungsrichtung beaufschlagt wird und wobei darüber hinaus - bei dieser Anordnung der Einblasdüse 8 - bereits Behandlungsgas aus der Behandlungszone 3 angesaugt wird. Daraus ergibt sich ein bevorzugtes Ausströmen des überschüssigen Behandlungsgases aus der Behandlungszone in die Kühlzone, während praktisch kein Behandlungsgas aus der Behandlungszone in die Einlaufzone 2 fließt und sogar das der Einlaufzone zugeführte Behandlungsgas eine überwiegende Strömung in die Behandlungszone hinein erhält. Wiederum sind die Strömungsverhältnisse in dieser Betriebssituation in der Figur durch Pfeile angedeutet.FIG. 2 shows a continuous furnace 1 with two blowing devices 7, 8 which can be switched alternately via the three-way valve 10 and only one further feed line 14 for treatment gas into the cooling zone 4. If the blowing device 7 is switched, a furnace gas flow against the direction of flow is generated in a manner similar to that just described. If a furnace train is to be produced in the direction of flow, treatment gas 8 is blown in the direction of the furnace exit into the cooling zone with the blowing device 8 arranged in the first third of the cooling zone 4 following the treatment zone 3, which in turn acts upon the entire atmosphere in the cooling zone with this flow direction and in addition - with this arrangement of the injection nozzle 8 - treatment gas is already sucked out of the treatment zone 3. This results in a preferred outflow of the excess treatment gas from the treatment zone into the cooling zone, while practically no treatment gas flows from the treatment zone into the inlet zone 2 and even the treatment gas supplied to the inlet zone receives a predominant flow into the treatment zone. The flow conditions in this operating situation are again indicated by arrows in the figure.

Insgesamt ist festzustellen, daß je nach Ausrichtung der Einblasvorrichtung eine in die entsprechende Richtung stabile Ofenströmung erzeugt werden kann. Zielrichtung dabei im Hinblick auf Wärmebehandlungen unter Behandlungsgas ist, den grundsätzlich nicht zu vermeidenden Einbruch von Luftbestandteilen in den Ofen - der bekanntermaßen durch einen hohen Durchsatz von Behandlungsgas durch den Ofen verringert werden kann - absichtlich einseitig auf der für das Wärmebehandlungsgut unschädlicheren Seite zuzulassen. Dies wird durch die gerichtete Strömung erreicht. Damit einhergehend sind wesentliche Einsparungen an Behandlungsgas im Vergleich zum konventionellen Verfahren möglich, da mit geringerer Gasmenge trotzdem in allen Ofenbereichen die Ofenatmosphäre in notwendiger Reinheit hergestellt werden kann. Dies ist einen wesentlicher Effekt des erfindungsgemäßen Verfahrens. Die Menge das eingeblasenen Behandlungsgases liegt dabei zwischen 3 und 35 %, vorzugsweise zwischen 5 und 20 %, der Menge, die der Wärmebehandlungseinrichtung auf konventionelle Art zugeführt wird.Overall, it should be noted that, depending on the orientation of the blowing device, a furnace flow that is stable in the corresponding direction can be generated. The aim with regard to heat treatments under treatment gas is the inevitable intrusion of air components into the furnace - which is known to be reduced by a high throughput of treatment gas through the furnace - intentionally allowed on one side on the side that is harmless to the heat treatment material. This is achieved through the directional flow. Along with this, significant savings in treatment gas are possible compared to the conventional process, since the furnace atmosphere can still be produced in all furnace areas with the necessary purity using a smaller amount of gas. This is an essential effect of the method according to the invention. The amount of the injected treatment gas is between 3 and 35%, preferably between 5 and 20%, of the amount that is supplied to the heat treatment device in a conventional manner.

Als Beispiel für eine Behandlung, bei dem das erfindungsgemäße Verfahren mit einem gegen die Durchlaufrichtung gerichteten Ofenzug angewendet werden kann, ist das Glühen von Nickel-Kupfer-Legierungen zu nennen, da wegen der hohen Korrosionsbeständigkeit dieser Werkstoffe das Eindringen von Luftanteilen, insbesondere Sauerstoff, in die Kühlzone zu keiner Verschlechterung des Glühergebnisses führt.An example of a treatment in which the method according to the invention can be used with a furnace train directed against the direction of flow is the annealing of nickel-copper alloys, since the penetration of air, especially oxygen, into the materials due to the high corrosion resistance of these materials the cooling zone does not deteriorate the annealing result.

Als weiteres Beispiel sei das Glühen von Stahl erwähnt, bei dem mit einem in Durchlaufrichtung gerichteten Ofenzug gearbeitet werden kann, da für Stahl im Eingangsbereich des Behandlungsofen ein gewisses Maß an Verunreinigungen aus der Luft, insbesondere bezogen auf Kohlendioxid, tolerierbar ist.As a further example, the annealing of steel should be mentioned, in which it is possible to work with a furnace train directed in the direction of passage, since a certain degree of contamination from the air, in particular based on carbon dioxide, is tolerable for steel in the entrance area of the treatment furnace.

Neben der Festlegung eines Ofenzuges ist es mit dem erfindungsgemäßen Verfahren auch möglich, durch Einblasen quer, also in etwa in 90 °, zur Durchlaufrichtung einen in Bezug zur Durchlaufrichtung ortsfesten Gaswirbel zu erzeugen, der in Durchlaufrichtung verlaufende Gasströmungen verhindert. Dies kann z.B. zur Abschottung von Ofenein- und - aussgängen gegenüber der Umgebungsluft dienen. Eine günstige, praktische Ausgestaltung dieser Variante der Erfindung erhält man durch zwei parallel angeordnete, bezüglich ihrer Ausblasrichtung gegeneinander ausgerichtete Einblasvorrichtungen der obenbeschriebenen Bauart, wie sie in Figur 4 gezeigt ist. Mit dieser Anordnung von Einblasvorrichtungen, die um ihre Achse drehbar sind, ist auch ein schräges, in verschiedenen Winkeln zur Durchlaufrichtung gerichtetes Einblasen von Behandlungsgas möglich. Durch geeignet koordinierte, insbesondere in gleicher Schräge bezüglich der Durchlaufrichtung ausgerichtete Orientierung der beiden Einblasvorrichtungen sind so ebenfalls Strömungen in oder gegen die Durchlaufrichtung in sehr effizienter Weise erzeugbar.In addition to the determination of an oven train, it is also possible with the method according to the invention, by blowing in transversely, ie at approximately 90 °, to the direction of flow to generate stationary gas vortices in relation to the direction of flow, which prevents gas flows running in the direction of flow. This can be used, for example, to isolate furnace inlets and outlets from the ambient air. A favorable, practical embodiment of this variant of the invention is obtained by two parallel arranged blowing devices of the type described above, with respect to their blow-out direction, as shown in FIG. With this arrangement of injection devices, which can be rotated about their axis, an oblique injection of treatment gas directed at different angles to the direction of flow is also possible. By suitably coordinated orientation of the two blowing devices, in particular oriented in the same incline with respect to the direction of flow, flows in or against the direction of flow can also be generated in a very efficient manner.

Mit dem erfindungsgemäßen Verfahren kann schließlich auch Einfluß auf eine in einem Behandlungsofen von vorne herein auftretende Strömung genommen werden. Herrscht z.B. in einer Ofenanlage aufgrund ungünstiger Luftzugverhältnisse in der die Ofenanlage umgebenden Halle eine unerwünschte Strömung, so ist die Anwendung des erfindungsgemäßen Verfahrens möglicherweise sogar in geregelter Version mit Ofenzugsensor und entsprechend regelbarem Einblasdruck eine geeignete Möglichkeit, einen gewünschten Ofenzug zu erzeugen.Finally, the method according to the invention can also be used to influence a flow occurring from the beginning in a treatment furnace. For example, in an oven system due to unfavorable drafts in the hall surrounding the oven system, the use of the method according to the invention, even in a controlled version with an oven draft sensor and a correspondingly adjustable injection pressure, is a suitable way of generating a desired oven draft.

Zusammenfassend kann festgestellt werden, daß das erfindungsgemäße Verfahren bei vielen Wärmebehandlungen in ökonomisch und/oder produktionstechnisch vorteilhafter Weise eingesetzt werden kann.In summary, it can be stated that the method according to the invention can be used in many heat treatments in an economically and / or technically advantageous manner.

Claims (9)

1. Verfahren zur Wärmebehandlung von Werkstücken in einer Behandlungsgasatmosphäre in einem Durchlaufofen mit Einlauf-, Behandlungs- und Kühlzone, dadurch gekennzeichnet, daß ein Teil des Behandlungsgases mit einem über dem normalen Einführdruck des Behandlungsgases liegenden Druck und gerichtet in eine oder mehrere Ofenzonen eingeblasen wird.1. A method for the heat treatment of workpieces in a treatment gas atmosphere in a continuous furnace with inlet, treatment and cooling zone, characterized in that part of the treatment gas is blown and directed into one or more furnace zones at a pressure above the normal introduction pressure of the treatment gas. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Einblasanteil des Behandlungsgases mit einem Überdruck von 1 bis 20 bar, vozugsweise 2 bis 6 bar, gerichtet eingeblasen wird.2. The method according to claim 1, characterized in that the blowing-in portion of the treatment gas with a positive pressure of 1 to 20 bar, preferably 2 to 6 bar, is injected directed. 3. Verfahren nach einem der Ansprüche 1 bis 2, dadurch gekennzeichnet, daß zur Erzeugung einer Behandlungsgasströmung im Ofen in oder gegen die Durchlaufrichtung der zu behandelnden Werkstücke der Einblasanteil des Behandlungsgases etwa im Mittelteil der Kühlzone des Durchlaufofens in der Richtung der zu erzeugenden Ofengasströmung eingeblasen wird.3. The method according to any one of claims 1 to 2, characterized in that for generating a treatment gas flow in the furnace in or against the direction of flow of the workpieces to be treated, the blowing portion of the treatment gas is blown approximately in the middle part of the cooling zone of the continuous furnace in the direction of the furnace gas flow to be generated . 4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Behandlungsgasströmung mit einem Ofenzugsensor gemessen wird und der Einblasdruck entsprechend diesem Meßwert und dem gewünschten Ofenzug eingestellt wird.4. The method according to any one of claims 1 to 3, characterized in that the treatment gas flow is measured with a furnace draft sensor and the injection pressure is set according to this measured value and the desired furnace draft. 5. Verfahren nach einem der Ansprüche 1 bis 2, dadurch gekennnzeichnet, daß Behandlungsgas quer oder beliebig schräg zur Durchlaufrichtung eingeblasen wird.5. The method according to any one of claims 1 to 2, characterized in that treatment gas is injected transversely or at any angle to the direction of flow. 6. Durchlaufofen zur Durchführung des Verfahrens nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß eine oder mehrere Einblasvorrichtungen (7, 8) in einer oder mehreren Ofenzonen (2, 3, 4) angeordnet und mit einer Behandlungsgasversorgung verbunden sind.6. Continuous furnace for carrying out the method according to one of claims 1 to 5, characterized in that one or more blowing devices (7, 8) in one or more furnace zones (2, 3, 4) are arranged and connected to a treatment gas supply. 7. Durchlaufofen nach Anspruch 6, dadurch gekennzeichnet, daß in einer oder mehreren Ofenzonen in einer Ebene quer zur Durchlaufrichtung der zu behandelnden Werkstücke zwei oder mehr Einblasvorrichtungen angeordnet und so koordiniert ausgerichtet sind, daß dadurch eine gewünschte Gasströmung entsteht.7. Continuous furnace according to claim 6, characterized in that in one or more furnace zones in one plane transverse to the direction of flow of the workpieces to be treated, two or more blowing devices are arranged and aligned so that a desired gas flow is created. 8. Einblasvorrichtung, dadurch gekennzeichnet, daß sie im wesentlichen aus einer geraden, länglichen Röhre (15) besteht, deren eines Ende bis auf eine oder mehrere Gasauslaßöffnungen (16) mit gewünschter Ausrichtung verschlossen ist und die über das andere Ende mit einer Behandlungsgasversorgung verbindbar ist.8. blowing device, characterized in that it consists essentially of a straight, elongated tube (15), one end of which is closed to one or more gas outlet openings (16) with the desired orientation and which can be connected to a treatment gas supply via the other end . 9. Einblasvorrichtung nach Anspruch 8, dadurch gekennzeichnet, daß sie zumindest teilweise um ihre Längsachse (18) drehbar gestaltet ist.9. blowing device according to claim 8, characterized in that it is designed at least partially rotatable about its longitudinal axis (18).
EP89114350A 1988-08-18 1989-08-03 Method of heat treating workpieces Expired - Lifetime EP0355520B1 (en)

Priority Applications (1)

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AT89114350T ATE104360T1 (en) 1988-08-18 1989-08-03 METHODS OF HEAT TREATMENT OF WORKPIECES.

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DE3828134A DE3828134A1 (en) 1988-08-18 1988-08-18 METHOD FOR THE HEAT TREATMENT OF WORKPIECES
DE3828134 1988-08-18

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EP0355520A2 true EP0355520A2 (en) 1990-02-28
EP0355520A3 EP0355520A3 (en) 1990-04-18
EP0355520B1 EP0355520B1 (en) 1994-04-13

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EP0524368A1 (en) * 1991-06-27 1993-01-27 Leybold Durferrit GmbH Automatic apparatus for monitoring and control of a vacuum thermal treatment furnace
EP1077267A1 (en) * 1999-08-18 2001-02-21 Patherm SA Apparatus for the continuous heat treatment of metal workpieces separately or in batches
WO2005035799A1 (en) * 2003-10-08 2005-04-21 Messer Austria Gmbh Method for heat-treating iron-containing materials
EP1842931A1 (en) * 2006-04-04 2007-10-10 Linde Aktiengesellschaft Method for heat treatment
EP1842930A1 (en) * 2006-04-04 2007-10-10 Linde Aktiengesellschaft Process for heat treatment
US7955450B2 (en) 2006-04-04 2011-06-07 Linde Aktiengesellschaft Method for heat treatment

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US3415503A (en) * 1967-08-18 1968-12-10 Btu Eng Corp Conditioned atmosphere furnace muffle
DE2601658A1 (en) * 1976-01-17 1977-07-28 J F Mahler Fa Cooling channel for continuous heat treatment furnace - where cold protective gas flows through channel in adjustable directions
EP0075438B1 (en) * 1981-09-19 1987-12-16 BOC Limited Heat treatment of metals

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0524368A1 (en) * 1991-06-27 1993-01-27 Leybold Durferrit GmbH Automatic apparatus for monitoring and control of a vacuum thermal treatment furnace
US5362031A (en) * 1991-06-27 1994-11-08 Leybold Durfrrit Gmbh Method and apparatus for the automatic monitoring of operating safety and for controlling the progress of the process in a vacuum heat-treatment oven
EP1077267A1 (en) * 1999-08-18 2001-02-21 Patherm SA Apparatus for the continuous heat treatment of metal workpieces separately or in batches
WO2005035799A1 (en) * 2003-10-08 2005-04-21 Messer Austria Gmbh Method for heat-treating iron-containing materials
EP1842931A1 (en) * 2006-04-04 2007-10-10 Linde Aktiengesellschaft Method for heat treatment
EP1842930A1 (en) * 2006-04-04 2007-10-10 Linde Aktiengesellschaft Process for heat treatment
US7955450B2 (en) 2006-04-04 2011-06-07 Linde Aktiengesellschaft Method for heat treatment

Also Published As

Publication number Publication date
ATE104360T1 (en) 1994-04-15
DE58907441D1 (en) 1994-05-19
ZA896284B (en) 1990-04-25
DE3828134A1 (en) 1990-02-22
EP0355520A3 (en) 1990-04-18
EP0355520B1 (en) 1994-04-13

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