EP0313889A1 - Vacuum furnace for the heat treatment of metallic work-pieces - Google Patents

Vacuum furnace for the heat treatment of metallic work-pieces Download PDF

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Publication number
EP0313889A1
EP0313889A1 EP88116478A EP88116478A EP0313889A1 EP 0313889 A1 EP0313889 A1 EP 0313889A1 EP 88116478 A EP88116478 A EP 88116478A EP 88116478 A EP88116478 A EP 88116478A EP 0313889 A1 EP0313889 A1 EP 0313889A1
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EP
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Prior art keywords
vacuum furnace
batch
cooling gas
thermal insulation
gas
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EP88116478A
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German (de)
French (fr)
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EP0313889B1 (en
Inventor
Paul Dipl.-Ing. Heilmann
Erwin Dipl.-Ing. Heumüller
Fritz Kalbfleisch
Friedrich Dr. Dipl.-Phys. Preisser
Rolf Schuster
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Evonik Operations GmbH
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Degussa GmbH
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    • 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • 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
    • 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
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or vacuum
    • 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
    • F27D7/04—Circulating atmospheres by mechanical means
    • 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B2005/062—Cooling elements
    • F27B2005/064—Cooling elements disposed in the furnace, around the chamber, e.g. coils
    • 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/14—Arrangements of heating devices
    • F27B2005/143—Heating rods disposed in the chamber
    • F27B2005/146—Heating rods disposed in the chamber the heating rods being in the tubes which conduct the heating gases
    • 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/161—Gas inflow or outflow
    • F27B2005/164—Air supply through a set of tubes with openings
    • 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
    • F27B5/00—Muffle furnaces; Retort furnaces; Other furnaces in which the charge is held completely isolated
    • F27B5/06—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B5/16—Arrangements of air or gas supply devices
    • F27B2005/166—Means to circulate the atmosphere
    • F27B2005/167—Means to circulate the atmosphere the atmosphere being recirculated through the treatment chamber by a turbine

Definitions

  • the invention relates to a vacuum furnace for the heat treatment of metallic workpieces with a cylindrical pressure housing, in which a batch space surrounded by axially aligned heat conductors and provided with thermal insulation and a gas cooling device are arranged, with which a cooling gas is passed through nozzles through the batch space and over a heat exchanger can.
  • Such vacuum furnaces are used in particular for the hardening of tools and components of all kinds made of various types of steel. Some of them can also be used for other heat treatments, e.g. B. Annealing and soldering.
  • DE-PSs 28 39 807 and 28 44 843 describe generic vacuum ovens. They essentially consist of a cylindrical pressure housing in which there is a batch chamber, which is delimited by thermal insulation walls and heated by heating elements, and a gas cooling device. The tools and components are heated in the batch chamber under vacuum to the austenitizing temperature and a cooled inert gas is circulated under pressure in the furnace for quenching. The cooling gas flows at high speed onto the hot batch, removes this thermal energy and is passed through a heat exchanger, where it is cooled and returned to the batch chamber. The cooling gas is introduced into the batch chamber according to DE-PS 28 39 807 via nozzles which are attached to separate, axially aligned gas inlet pipes.
  • This vacuum oven should ensure the fastest possible, even cooling of the heated batches, be as simple as possible and be able to be heated as quickly as possible.
  • heat conductors are designed as tubes, are provided with bores towards the batch space and are connected to a cooling gas distribution device via electrical insulating pieces.
  • the cooling gas distribution device is preferably provided with a fan which pushes the cooling gas through the heating pipes and sucks it in again from the batch space.
  • the wall of the thermal insulation in the area of the cooling gas distribution device is provided with a closable opening. This means that a heating gas flow can be maintained in the furnace interior bypassing the heat exchanger during the heating period of the batches.
  • Figures 1 and 2 schematically show longitudinal sections through an embodiment of a vacuum oven according to the invention, Figure 1 showing the oven in the heating phase up to about 750 ° C and Figure 2 in the cooling phase.
  • the furnace consists of a cylindrical pressure housing (1), one end face of which is designed as a door (2) through which the furnace can be loaded and unloaded.
  • the batch space (3) is delimited on the outside by thermal insulation (4) in the form of a cylindrical tube, which consists of a thermal insulation material and is provided on the end faces with corresponding walls, at least one wall (5) of which is movable.
  • This thermal insulation (4) shields the radiation in the batch space (3) from the outside, so that only slight energy losses occur.
  • the electrical heating conductors (6) are arranged axially in the batch space (3), which are designed as heating pipes and are provided with holes (7) towards the batch space (3).
  • These heating tubes (6) have, for example, a wall thickness of 1 to 3 mm and a clear width of 40 to 150 mm.
  • the diameter of the bores (7) is dimensioned such that the sum of the areas of the bores of a heating tube corresponds to the area of the clear width.
  • the heating pipes (6) are attached to the cooling gas distribution device (9) via electrical insulating pieces (8), which are connected to the drive motor (10) and the fan (11) on the side opposite the door (2) is housed in the pressure housing.
  • the wall of the thermal insulation (4) adjacent to the cooling gas distribution device (9) is provided with an opening (12) which can be closed and opened with a slide (13).
  • the water-cooled heat exchanger tubes (14) are accommodated between the pressure housing (1) and the thermal insulation (4).
  • the batch space (3) After loading the batch space (3) with tools, for example, it is flooded with an inert gas and heated.
  • the slide (13) opens the opening (12) in the thermal insulation ( Figure 1) so that the inert gas can be pressed by the fan (11) into the heating pipes (6), from where it passes through the holes (7) , which are distributed over the length of the heating pipes, penetrates into the batch space (3) and is returned to the fan (11) through the opening (12) in the thermal insulation.
  • the inert gas Since the inert gas is fed in via the heating pipes (6), it quickly increases in temperature, which results in the batch being heated quickly and homogeneously by the hot gas in the dark radiation region. Due to the hot gas flowing directly onto the batch, the batch is evenly heated internally.
  • This heating process under protective gas is used up to about 750 ° C. In the case of hardening treatments in which heating has to be carried out up to approximately 1300 ° C., the inert gas is then removed from the furnace and the further heating is carried out only by heat radiation
  • the furnace is flooded with cold inert gas with excess pressure when the opening (12) is closed.
  • the wall (5) of the thermal insulation (4) is lifted off the cylindrical tube, so that a gap is created and the batch space (3) with the space between Pressure housing (1) and thermal insulation (4) is connected ( Figure 2).
  • the cooling gas is pressed by the fan (11) over the cooled heating pipes (6) at high speed into the batch space (3), from where it flows back through the heat exchanger pipes (14) into the cooling gas distribution device (9) and is circulated again.
  • inert gases are used, combined with high gas pressures and gas velocities, quenching intensities are achieved with the vacuum furnaces according to the invention which are comparable to those achievable in oil quenching baths.
  • other types of steel than previously can be quenched and hardened with gas cooling.
  • the heating tubes (6) which also serve as gas supply tubes, preferably consist of carbon fiber-reinforced carbon.
  • the electrically conductive cross-section of the heating pipes, which is decisive for heat generation, and the internal width of the heating pipes, which is decisive for the gas volume flow, must be coordinated.
  • the combination of the heating element and the gas supply pipe results in a significant simplification of the manufacturing process in the manufacture of these furnaces.
  • the cooling gas is pumped out of the furnace interior with a compressor after the quenching process and conveyed into a high-pressure accumulator, from where it is available for further applications.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Furnace Details (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Thermally Insulated Containers For Foods (AREA)
  • Meat, Egg Or Seafood Products (AREA)
  • Plural Heterocyclic Compounds (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

A vacuum furnace for heat treatment of metallic workpieces wherein the heat conductors are formed as conduits fitted with bore holes and connected by electrical insulators to coolant gas distributor.

Description

Die Erfindung betrifft einen Vakuumofen zur Wärmebehandlung metallischer Werkstücke mit einem zylindrischen Druckgehäuse, in dem ein von axial ausgerichteten Heizleitern umgebener, mit einer thermischen Isolierung versehener Chargenraum und eine Gaskühleinrichtung angeordnet sind, mit der ein Kühlgas über Düsen durch den Chargenraum und über einen Wärmetauscher geleitet werden kann. Solche Vakuumöfen werden insbesondere für das Härten von Werkzeugen und Bauteilen aller Art aus vielerlei Stahlsorten benutzt. Zum Teil sind sie auch für andere Wärmebehandlungen einsetzbar, z. B. Glühen und Löten.The invention relates to a vacuum furnace for the heat treatment of metallic workpieces with a cylindrical pressure housing, in which a batch space surrounded by axially aligned heat conductors and provided with thermal insulation and a gas cooling device are arranged, with which a cooling gas is passed through nozzles through the batch space and over a heat exchanger can. Such vacuum furnaces are used in particular for the hardening of tools and components of all kinds made of various types of steel. Some of them can also be used for other heat treatments, e.g. B. Annealing and soldering.

In den DE-PSen 28 39 807 und 28 44 843 werden gattungsgemäße Vakuumöfen beschrieben. Sie bestehen im wesentlichen aus einem zylindrischen Druckgehäuse, in dem sich eine von thermischen Isolationswänden begrenzte, mit Heizelementen beheizte Chargenkammer und eine Gaskühleinrichtung befinden. Die Werkzeuge und Bauteile werden in der Chargenkammer unter Vakuum auf die Austenitisierungstemperatur aufgeheizt und zum Abschrecken wird ein gekühltes Inertgas unter Druck im Ofen umgewälzt. Das Kühlgas strömt dabei mit hoher Geschwin­digkeit auf die heiße Charge, entzieht dieser Wärmeenergie und wird über einen Wärmetauscher geleitet, wo es abgekühlt und wieder der Chargenkammer zugeführt wird. Die Einleitung des Kühlgases in die Chargenkammer erfolgt gemäß DE-PS 28 39 807 über Düsen, die auf gesonderten, axial ausgerichte­ten Gaseinleitrohren angebracht sind. Nachteil dieser Konstuktion ist der hohe Material- und Fertigungsaufwand für die Gaseinleitrohre im Ofen. Rohre und Düsen müssen aus hochtemperaturbeständigem Material bestehen. Die in der DE-PS 28 44 843 verwendeten Ventilatoren besitzen den Nachteil, daß das Kühlgas im beträchtlichen Umfang nur an der heißen Chargeoberfläche entlangströmt und nicht ins Chargeninnere eindringt.DE-PSs 28 39 807 and 28 44 843 describe generic vacuum ovens. They essentially consist of a cylindrical pressure housing in which there is a batch chamber, which is delimited by thermal insulation walls and heated by heating elements, and a gas cooling device. The tools and components are heated in the batch chamber under vacuum to the austenitizing temperature and a cooled inert gas is circulated under pressure in the furnace for quenching. The cooling gas flows at high speed onto the hot batch, removes this thermal energy and is passed through a heat exchanger, where it is cooled and returned to the batch chamber. The cooling gas is introduced into the batch chamber according to DE-PS 28 39 807 via nozzles which are attached to separate, axially aligned gas inlet pipes. The disadvantage of this design is the high cost of materials and manufacturing for the gas inlet pipes in the furnace. Pipes and nozzles must be made of high temperature resistant material. The fans used in DE-PS 28 44 843 have the disadvantage that the cooling gas flows to a considerable extent only along the hot batch surface and does not penetrate into the interior of the batch.

Aus der DE-OS 19 19 493 ist es bekannt, im Temperaturbereich zwischen Raumtemperatur und etwa 750 °C das Aufheizen der Charge zu beschleunigen, indem man im Ofen ein Inertgas mittels eines Ventilators umwälzt und so neben der Strahlung eine Konvektion erzeugt. Aber auch hierbei ist der Wärmeübergang zwischen Heizleiter und Charge nicht optimal.From DE-OS 19 19 493 it is known to accelerate the heating of the batch in the temperature range between room temperature and about 750 ° C. by circulating an inert gas in the furnace by means of a fan and thus producing a convection in addition to the radiation. But even here the heat transfer between the heating conductor and the batch is not optimal.

Es war daher Aufgabe der vorliegenden Erfindung, einen Vakuumofen zur Wärmebehandlung metallischer Werkstücke mit einem zylindrischen Druckgehäuse zu konstruieren, in dem ein von axial ausgerichteten Heizleitern umgebener, mit einer thermischen Isolierung versehender Chargenraum und eine Gaskühleinrichtung angeordnet sind, mit der ein Kühlgas über Düsen durch den Chargenraum und über einen Wärmetauscher geleitet werden kann. Dieser Vakuumofen sollte eine möglichst schnelle und gleichmäßige Abkühlung der aufgeheizten Chargen gewährleisten, eine möglichst einfache Konstruktion besitzen und möglichst rasch aufheizbar sein.It was therefore an object of the present invention to construct a vacuum furnace for the heat treatment of metallic workpieces with a cylindrical pressure housing in which a batch space surrounded by axially aligned heating conductors, provided with thermal insulation, and a gas cooling device are arranged, with which a cooling gas is passed through nozzles through the Batch room and can be passed through a heat exchanger. This vacuum oven should ensure the fastest possible, even cooling of the heated batches, be as simple as possible and be able to be heated as quickly as possible.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Heizleiter als Rohre ausgebildet, zum Chargenraum hin mit Bohrungen versehen und über elektrische Isolierstücke mit einer Kühlgasverteilungsvorrichtung verbunden sind.This object is achieved in that the heat conductors are designed as tubes, are provided with bores towards the batch space and are connected to a cooling gas distribution device via electrical insulating pieces.

Vorzugsweise ist die Kühlgasverteilungsvorrichtung mit einem Ventilator versehen, der das Kühlgas durch die Heizrohre drückt und aus dem Chargenraum wieder ansaugt.The cooling gas distribution device is preferably provided with a fan which pushes the cooling gas through the heating pipes and sucks it in again from the batch space.

Weiterhin ist es von Vorteil, wenn die Wand der thermischen Isolierung im Bereich der Kühlgasverteilungsvorrichtung mit einer verschließbaren Öffnung versehen ist. Damit kann während der Aufheizperiode der Chargen eine Heizgasströmung unter Umgehung des Wärmetauschers im Ofeninnenraum aufrechterhalten werden.It is also advantageous if the wall of the thermal insulation in the area of the cooling gas distribution device is provided with a closable opening. This means that a heating gas flow can be maintained in the furnace interior bypassing the heat exchanger during the heating period of the batches.

Bei teuren Kühlgasen ist es ebenfalls vorteilhaft, den Ofen mit einer Rückgewinnungsanlage für das Kühlgas zu versehen.In the case of expensive cooling gases, it is also advantageous to provide the furnace with a recovery system for the cooling gas.

Die Abbildungen 1 und 2 zeigen schematisch Längsschnitte durch ein Ausführungsbeispiel eines erfindungsgemäßen Vakuumofens, wobei Abbildung 1 den Ofen in der Aufheizphase bis etwa 750 °C und Abbildung 2 in der Abkühlphase widergibt.Figures 1 and 2 schematically show longitudinal sections through an embodiment of a vacuum oven according to the invention, Figure 1 showing the oven in the heating phase up to about 750 ° C and Figure 2 in the cooling phase.

Der Ofen besteht aus einem zylindrischen Druckgehäuse (1), dessen eine Stirnfläche als Tür (2) ausgebildet ist, über die der Ofen be- und entladen werden kann. Der Chargenraum (3) wird nach außen von einer thermischen Isolierung (4) in Form eines zylindrischen Rohres begrenzt, das aus einem thermischen Isoliermaterial besteht und an den Stirnflächen mit entsprechenden Wänden versehen ist, von denen wenigstens eine Wand (5) bewegbar ist. Diese thermische Isolierung (4) schirmt die Strahlung im Chargenraum (3) nach außen ab, so daß nur geringe Energieverluste entstehen. Innerhalb der thermischen Isolierung (4) sind im Chargenraum (3) ringsum die elektrischen Heizleiter (6) axial angeordnet, die als Heizrohre ausgebildet und zum Chargenraum (3) hin mit Bohrungen (7) versehen sind. Diese Heizrohre (6) haben beispielsweise eine Wandstärke von 1 bis 3 mm und eine lichten Weite von 40 bis 150 mm. Der Durchmesser der Bohrungen (7) wird so bemessen, daß die Summe der Flächen der Bohrungen eines Heizrohres der Fläche der lichten Weite entspricht. Die Heizrohre (6) sind über elektrische Isolierstücke (8) an der Kühlgas­verteilungsvorrichtung (9) befestigt, die mit dem Antriebs­ motor (10) und dem Ventilator (11) an der der Tür (2) gegenüberliegenden Seite im Druckgehäuse untergebracht ist. Die der Kühlgasverteilungsvorrichtung (9) benachbarte Wand der thermischen Isolierung (4) ist mit einer Öffnung (12) versehen, die mit einem Schieber (13) verschlossen und geöffnet werden kann. Zwischen dem Druckgehäuse (1) und der thermischen Isolierung (4) sind die wassergekühlten Wärmeaustauscherrohre (14) untergebracht.The furnace consists of a cylindrical pressure housing (1), one end face of which is designed as a door (2) through which the furnace can be loaded and unloaded. The batch space (3) is delimited on the outside by thermal insulation (4) in the form of a cylindrical tube, which consists of a thermal insulation material and is provided on the end faces with corresponding walls, at least one wall (5) of which is movable. This thermal insulation (4) shields the radiation in the batch space (3) from the outside, so that only slight energy losses occur. Within the thermal insulation (4), the electrical heating conductors (6) are arranged axially in the batch space (3), which are designed as heating pipes and are provided with holes (7) towards the batch space (3). These heating tubes (6) have, for example, a wall thickness of 1 to 3 mm and a clear width of 40 to 150 mm. The diameter of the bores (7) is dimensioned such that the sum of the areas of the bores of a heating tube corresponds to the area of the clear width. The heating pipes (6) are attached to the cooling gas distribution device (9) via electrical insulating pieces (8), which are connected to the drive motor (10) and the fan (11) on the side opposite the door (2) is housed in the pressure housing. The wall of the thermal insulation (4) adjacent to the cooling gas distribution device (9) is provided with an opening (12) which can be closed and opened with a slide (13). The water-cooled heat exchanger tubes (14) are accommodated between the pressure housing (1) and the thermal insulation (4).

Nach dem Beladen des Chargenraums (3) mit beispielsweise Werkzeugen wird dieser mit einem Inertgas geflutet und aufgeheizt. Der Schieber (13) gibt die Öffnung (12) in der thermischen Isolierung frei (Abbildung 1), so daß das Inertgas durch den Ventilator (11) in die Heizrohre (6) gedrückt werden kann, von wo es über die Bohrungen (7), die über die Länge der Heizrohre verteilt sind, in den Chargenraum (3) eindringt und durch die Öffnung (12) in der thermischen Isolierung wieder zum Ventilator (11) zurückgeführt wird. Da das Inertgas über die Heizrohre (6) zugeleitet wird, nimmt es sehr rasch deren Temperatur an, was ein schnelles und homogenes Aufheizen der Charge durch das heiße Gas im Dunkelstrahlungsbereich zur Folge hat. Durch das direkte Anströmen der Charge mit dem heißen Gas wird die Charge gleichmäßig auch im Innern aufgeheizt. Dieser Aufheizungs­vorgang unter Schutzgas wird bis etwa 750 °C genutzt. Bei Härtebehandlungen, bei denen bis etwa 1300 °C erhitzt werden muß, wird dann das Inertgas aus dem Ofen entfernt und die weitere Erwärmung nur durch Wärmestrahlung vorgenommen, die in diesem Temperaturbereich sehr wirksam ist.After loading the batch space (3) with tools, for example, it is flooded with an inert gas and heated. The slide (13) opens the opening (12) in the thermal insulation (Figure 1) so that the inert gas can be pressed by the fan (11) into the heating pipes (6), from where it passes through the holes (7) , which are distributed over the length of the heating pipes, penetrates into the batch space (3) and is returned to the fan (11) through the opening (12) in the thermal insulation. Since the inert gas is fed in via the heating pipes (6), it quickly increases in temperature, which results in the batch being heated quickly and homogeneously by the hot gas in the dark radiation region. Due to the hot gas flowing directly onto the batch, the batch is evenly heated internally. This heating process under protective gas is used up to about 750 ° C. In the case of hardening treatments in which heating has to be carried out up to approximately 1300 ° C., the inert gas is then removed from the furnace and the further heating is carried out only by heat radiation, which is very effective in this temperature range.

Zum Abschrecken der erhitzten Charge wird bei geschlossener Öffnung (12) der Ofen mit kaltem Inertgas mit Überdruck geflutet. Dabei wird die Wand (5) der thermischen Isolierung (4) von dem zylindrischen Rohr abgehoben, so daß ein Spalt entsteht und der Chargenraum (3) mit dem Raum zwischen Druckgehäuse (1) und thermischer Isolierung (4) in Verbindung steht (Abbildung 2). Das Kühlgas wird vom Ventilator (11) über die erkalteten Heizrohre (6) mit großer Geschwindigkeit in den Chargenraum (3) gedrückt, von wo aus es über die Wärmetauscherrohre (14) in die Kühlgasverteilungsvorrichtung (9) zurückfließt und erneut umgewälzt wird. Bei Verwendung entsprechender Inertgase, verbunden mit hohen Gasdrücken und Gasgeschwindigkeiten, erreicht man mit den erfindungsgemäßen Vakuumöfen Abschreck­intensitäten, die mit den in Ölabschreckbädern erreichbaren vergleichbar sind. Dadurch können auch andere Stahltypen als bisher mit einer Gaskühlung abgeschreckt und gehärtet werden.To quench the heated batch, the furnace is flooded with cold inert gas with excess pressure when the opening (12) is closed. The wall (5) of the thermal insulation (4) is lifted off the cylindrical tube, so that a gap is created and the batch space (3) with the space between Pressure housing (1) and thermal insulation (4) is connected (Figure 2). The cooling gas is pressed by the fan (11) over the cooled heating pipes (6) at high speed into the batch space (3), from where it flows back through the heat exchanger pipes (14) into the cooling gas distribution device (9) and is circulated again. If appropriate inert gases are used, combined with high gas pressures and gas velocities, quenching intensities are achieved with the vacuum furnaces according to the invention which are comparable to those achievable in oil quenching baths. As a result, other types of steel than previously can be quenched and hardened with gas cooling.

Die Heizrohre (6), die gleichzeitig als Gaszuleitungsrohre dienen, bestehen bevorzugt aus carbonfaserverstärktem Kohlenstoff. Der elektrisch leitende Querschnitt der Heizrohre, der für die Wärmeerzeugung maßgebend ist, und die für den Gasvolumenstrom maßgeblische innere Weite der Heizrohre müssen dabei aufeinander abgestimmt sein. Die Kombination von Heizelement und Gaszuleitungsrohr bringt eine wesentliche fertigungstechnische Vereinfachung bei der Herstellung dieser Öfen mit sich.The heating tubes (6), which also serve as gas supply tubes, preferably consist of carbon fiber-reinforced carbon. The electrically conductive cross-section of the heating pipes, which is decisive for heat generation, and the internal width of the heating pipes, which is decisive for the gas volume flow, must be coordinated. The combination of the heating element and the gas supply pipe results in a significant simplification of the manufacturing process in the manufacture of these furnaces.

Wird zum Abschrecken ein teures Inertgas verwendet, so ist es vorteilhaft, dieses wieder zurückzugewinnen. Zu diesem Zweck wird das Kühlgas nach Beendigung des Abschreckvorganges mit einem Kompressor aus dem Ofeninnenraum abgepumpt und in einen Hochdruckspeicher gefördert, von wo aus es für weitere Anwendungen zur Verfügung steht.If an expensive inert gas is used for quenching, it is advantageous to recover it. For this purpose, the cooling gas is pumped out of the furnace interior with a compressor after the quenching process and conveyed into a high-pressure accumulator, from where it is available for further applications.

Claims (4)

1. Vakuumofen zur Wärmebehandlung metallischer Werkstücke mit einem zylindrischen Druckgehäuse, in dem ein von axial ausgerichteten Heizleitern umgebener, mit einer thermischen Isolierung versehener Chargenraum und eine Gaskühleinrich­tung angeordnet sind, mit der ein Kühlgas über Düsen durch den Chargenraum und über einen Wärmetauscher geleitet werden kann,
dadurch gekennzeichnet,
daß die Heizleiter (6) als Rohre ausgebildet, zum Chargen­raum hin mit Bohrungen (7) versehen und über elektrische Isolierstücke (8) mit einer Kühlgasverteilungsvorrichtung (9) verbunden sind.1.Vacuum furnace for the heat treatment of metallic workpieces with a cylindrical pressure housing, in which a batch space surrounded by axially aligned heating conductors and provided with thermal insulation and a gas cooling device are arranged, with which a cooling gas can be passed through nozzles through the batch space and over a heat exchanger,
characterized,
that the heating conductors (6) are designed as tubes, are provided with holes (7) towards the batch space and are connected to a cooling gas distribution device (9) via electrical insulating pieces (8). 2. Vakuumofen nach Anspruch 1,
dadurch gekennzeichnet,
daß die Kühlgasverteilungsvorrichtung (9) mit einem Ventilator (11) versehen ist.2. Vacuum furnace according to claim 1,
characterized,
that the cooling gas distribution device (9) is provided with a fan (11). 3. Vakuumofen nach Anspruch 1 und 2,
dadurch gekennzeichnet,
daß die Wand der thermischen Isolierung (4) im Bereich der Kühlgasverteilungsvorrichtung (9) mit einer verschließbaren Öffnung (12) versehen ist.3. Vacuum furnace according to claim 1 and 2,
characterized,
that the wall of the thermal insulation (4) in the area of the cooling gas distribution device (9) is provided with a closable opening (12). 4. Vakuumofen nach Anspruch 1 bis 3,
dadurch gekennzeichnet,
daß er mit einer Rückgewinnungsanlage für das Kühlgas versehen ist.4. Vacuum furnace according to claim 1 to 3,
characterized,
that it is provided with a recovery system for the cooling gas.
EP88116478A 1987-10-28 1988-10-05 Vacuum furnace for the heat treatment of metallic work-pieces Expired - Lifetime EP0313889B1 (en)

Priority Applications (1)

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AT88116478T ATE65800T1 (en) 1987-10-28 1988-10-05 VACUUM FURNACE FOR HEAT TREATMENT OF METALLIC WORKPIECES.

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Application Number Priority Date Filing Date Title
DE3736502 1987-10-28
DE3736502A DE3736502C1 (en) 1987-10-28 1987-10-28 Vacuum furnace for the heat treatment of metallic workpieces

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EP0313889B1 EP0313889B1 (en) 1991-07-31

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EP0344413B1 (en) * 1988-05-31 1993-05-12 Ipsen Industries International Gesellschaft Mit Beschränkter Haftung Furnace for the heat treatment of iron and steel parts
WO1994016278A1 (en) * 1993-01-14 1994-07-21 Seco/Warwick Spólka Z O.O. (Ltd) Vacuum furnace for thermal treatment
EP0727498A1 (en) * 1995-01-23 1996-08-21 ALD Vacuum Technologies GmbH Process and installation for cooling workpieces, in particular for hardening
WO1997000974A1 (en) * 1995-06-22 1997-01-09 Aga Aktiebolag (Publ) A method and an apparatus for the treatment of components by a gas mixture
DE10117987A1 (en) * 2001-04-10 2002-10-31 Ald Vacuum Techn Ag Charging frame used for heat treatment and cooling of metal parts, e.g. roller bearing parts, to be hardened is partially screened over the height of one side
DE102019204869A1 (en) * 2019-04-05 2020-10-08 Audi Ag Quenching device for batch cooling of metal components

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EP0344413B1 (en) * 1988-05-31 1993-05-12 Ipsen Industries International Gesellschaft Mit Beschränkter Haftung Furnace for the heat treatment of iron and steel parts
WO1994016278A1 (en) * 1993-01-14 1994-07-21 Seco/Warwick Spólka Z O.O. (Ltd) Vacuum furnace for thermal treatment
EP0727498A1 (en) * 1995-01-23 1996-08-21 ALD Vacuum Technologies GmbH Process and installation for cooling workpieces, in particular for hardening
WO1997000974A1 (en) * 1995-06-22 1997-01-09 Aga Aktiebolag (Publ) A method and an apparatus for the treatment of components by a gas mixture
US5938866A (en) * 1995-06-22 1999-08-17 Aga Aktiebolag Method and an apparatus for the treatment of components by a gas mixture
DE10117987A1 (en) * 2001-04-10 2002-10-31 Ald Vacuum Techn Ag Charging frame used for heat treatment and cooling of metal parts, e.g. roller bearing parts, to be hardened is partially screened over the height of one side
DE102019204869A1 (en) * 2019-04-05 2020-10-08 Audi Ag Quenching device for batch cooling of metal components

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JPH01142018A (en) 1989-06-02
YU46575B (en) 1993-11-16
FI884514A (en) 1989-04-29
FI884514A0 (en) 1988-09-30
FI85386B (en) 1991-12-31
AU2440588A (en) 1989-05-04
PL156379B1 (en) 1992-03-31
ZA886832B (en) 1989-05-30
DE3864008D1 (en) 1991-09-05
BG49829A3 (en) 1992-02-14
AU601084B2 (en) 1990-08-30
BR8805558A (en) 1989-07-11
DE3736502C1 (en) 1988-06-09
NO169783B (en) 1992-04-27
EP0313889B1 (en) 1991-07-31
FI85386C (en) 1992-04-10
DK164747B (en) 1992-08-10
CN1033840A (en) 1989-07-12
DK164747C (en) 1992-12-28
YU193888A (en) 1990-04-30
DK596488A (en) 1989-04-29
DK596488D0 (en) 1988-10-27
NO169783C (en) 1992-08-05
HUT49652A (en) 1989-10-30
ES2023994B3 (en) 1992-02-16
NO884390L (en) 1989-05-02
CS711288A3 (en) 1992-05-13
ATE65800T1 (en) 1991-08-15
US4869470A (en) 1989-09-26
PT88895A (en) 1989-09-14
CN1015474B (en) 1992-02-12
DD283455A5 (en) 1990-10-10
HU199903B (en) 1990-03-28
PT88895B (en) 1997-02-28
IL87761A0 (en) 1989-02-28
NO884390D0 (en) 1988-10-04
CS276378B6 (en) 1992-05-13
CA1313043C (en) 1993-01-26
PL275470A1 (en) 1989-05-02
IN170643B (en) 1992-04-25
SU1813194A3 (en) 1993-04-30
IL87761A (en) 1993-01-31

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