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EP0057385B1 - Method for the direct electrical resistance heating of metal workpieces - Google Patents

Method for the direct electrical resistance heating of metal workpieces Download PDF

Info

Publication number
EP0057385B1
EP0057385B1 EP82100407A EP82100407A EP0057385B1 EP 0057385 B1 EP0057385 B1 EP 0057385B1 EP 82100407 A EP82100407 A EP 82100407A EP 82100407 A EP82100407 A EP 82100407A EP 0057385 B1 EP0057385 B1 EP 0057385B1
Authority
EP
European Patent Office
Prior art keywords
periods
resistance heating
temperature
workpiece
current flow
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
Application number
EP82100407A
Other languages
German (de)
French (fr)
Other versions
EP0057385A3 (en
EP0057385A2 (en
Inventor
Klaus-Michael Dr. Ing. Petzold
Gerald Dipl.-Ing. Werthmann
Herbert Dr. Mühe
Gregor Dipl.-Phys. Müller
Werner Prof.Dr.Ing. Schirmer
Roland Dipl.-Ing. Lippmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VEB Draht- und Seilwerk Rothenburg
Original Assignee
VEB Draht- und Seilwerk Rothenburg
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by VEB Draht- und Seilwerk Rothenburg filed Critical VEB Draht- und Seilwerk Rothenburg
Publication of EP0057385A2 publication Critical patent/EP0057385A2/en
Publication of EP0057385A3 publication Critical patent/EP0057385A3/en
Application granted granted Critical
Publication of EP0057385B1 publication Critical patent/EP0057385B1/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/0004—Devices wherein the heating current flows through the material to be heated
    • H05B3/0009—Devices wherein the heating current flows through the material to be heated the material to be heated being in motion
    • 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
    • C21D1/34—Methods of heating
    • C21D1/40—Direct resistance heating

Definitions

  • the invention relates to a method for the direct electrical resistance heating of metallic workpieces, in which, in addition, the temperature is influenced in certain time segments perpendicular to the direction of current flow by means of energy from the outside.
  • the surface temperature of the workpiece that has been established has basically been used to determine the electrical parameters (current, voltage) without taking into account the temperature distribution perpendicular to the direction of current flow, which is the result of heating and radiation conditions. This applies to all known methods for the direct electrical resistance heating of metallic workpieces (US Pat. No. 1,704,036).
  • the aim of the invention is to avoid the deficiencies of the prior art by using a method which enables the setting of targeted temperature distributions in a metallic workpiece perpendicular to the direction of current flow.
  • the invention has for its object to produce a temperature distribution optimally adapted to the end purpose perpendicular to the direction of current flow with direct electrical resistance heating of metallic workpieces, the dependence of the specific electrical resistance on the temperature being used to influence the temperature distribution.
  • the object is achieved in that defined energy offers act on the metallic workpiece so briefly that there is no temperature compensation over the cross-section of the workpiece within these time periods of the additional energy offers, as a result of which the temperature distribution in the workpiece arises unevenly perpendicular to the direction of current flow.
  • the time periods of the additional energy offers from the outside are before the resistance heating of the workpiece is initiated.
  • these periods of additional temperature influence can also lie within the periods of direct electrical resistance heating of the workpiece or before and within the periods of resistance heating.
  • the additional energy offers are provided by temperature supply and / or temperature dissipation.
  • the surface temperature is warmed to a depth of 0.5 mm to 200 ° C by an external heating device in the form of a cylindrical, electrically heated high-performance furnace.
  • an external heating device in the form of a cylindrical, electrically heated high-performance furnace.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Control Of Resistance Heating (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Resistance Heating (AREA)
  • Furnace Details (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

1. A method for direct electric resistance heating of metallic workpieces where, in addition to this, a temperature influence perpendicularly to the direction of current flow is effected by energy offers from outside within specific periods, characterized in that defined energy offers act for such a short time that no temperature compensation takes place across the section of the workpiece within these periods and, consequently, the temperature distribution perpendicularly to the direction of current flow is non-uniform.

Description

Die Erfindung betrifft ein Verfahren zur direkten elektrischen Widerstandserwärmung von metallischen Werkstücken, bei dem ausserdem in bestimmten Zeitabschnitten eine Temperaturbeeinflussung senkrecht zur Stromflussrichtung durch Energieangebote von aussen vorgenommen wird.The invention relates to a method for the direct electrical resistance heating of metallic workpieces, in which, in addition, the temperature is influenced in certain time segments perpendicular to the direction of current flow by means of energy from the outside.

Bei der direkten elektrischen Widerstandserwärmung erfolgt die Erwärmung durch direkte Umsetzung von elektrischer Energie in Wärme im stromdurchflossenen Werkstück. Die Temperaturverteilung im erwärmten Werkstück hängt bekanntlich ab

  • - von der Stromstärke, der Dichte, der spezifischen Wärme und der spezifischen elektrischen Leitfähigkeit des jeweiligen Materials bezüglich der Umwandlung elektrischer Energie in Wärme und
  • - vom Wärmeleitungskoeffizient, der Wärmeübergangszahl, der Dichte und der spezifischen Wärme des jeweiligen Materials bezüglich der Abstrahlbedingungen der Wärme an die Umgebung.
With direct electrical resistance heating, the heating takes place through direct conversion of electrical energy into heat in the current-carrying workpiece. As is well known, the temperature distribution in the heated workpiece depends
  • - The current strength, the density, the specific heat and the specific electrical conductivity of the respective material with regard to the conversion of electrical energy into heat and
  • - From the heat conduction coefficient, the heat transfer coefficient, the density and the specific heat of the respective material with regard to the radiation conditions of the heat to the environment.

Bisher wurde grundsätzlich die sich einstellende Oberflächentemperatur des Werkstückes zur Festlegung der elektrischen Parameter (Strom, Spannung) verwendet, ohne auf die Temperaturverteilung senkrecht zur Stromflussrichtung Rücksicht zu nehmen, die die Resultierende aus Erwärmungs- und Abstrahlbedingungen ist. Das trifft zu für alle bekannten Verfahren zur direkten elektrischen Widerstandserwärmung von metallischen Werkstücken (US-PS-1 704 036).So far, the surface temperature of the workpiece that has been established has basically been used to determine the electrical parameters (current, voltage) without taking into account the temperature distribution perpendicular to the direction of current flow, which is the result of heating and radiation conditions. This applies to all known methods for the direct electrical resistance heating of metallic workpieces (US Pat. No. 1,704,036).

Im Resultat von Erwärmungs- und Abstrahlbedingungen stellt sich stets über dem Querschnitt eine ganz bestimmte Temperaturverteilung ein, die man als gegeben hinnimmt. Das ist zugleich der Nachteil des Standes der Technik, da bezüglich eines zu lösenden Erwärmungsproblems die sich einstellende Temperaturverteilung senkrecht zur Stromflussrichtung in der Mehrzahl aller Fälle nicht diejenige ist, die zur optimalen Problemlösung führt.As a result of heating and radiation conditions, there is always a very specific temperature distribution across the cross-section, which is taken for granted. At the same time, this is the disadvantage of the prior art, since in relation to a heating problem to be solved, the temperature distribution that arises perpendicular to the direction of current flow is not the one that leads to the optimal problem solution in most cases.

Ziel der Erfindung ist die Vermeidung der Mängel des Standes der Technik durch Anwendung eines Verfahrens, das die Einstellung gezielter Temperaturverteilungen in einem metallischen Werkstück senkrecht zur Stromflussrichtung ermöglicht.The aim of the invention is to avoid the deficiencies of the prior art by using a method which enables the setting of targeted temperature distributions in a metallic workpiece perpendicular to the direction of current flow.

Der Erfindung liegt die Aufgabe zugrunde, eine dem Endzweck optimal angepasste Temperaturverteilung senkrecht zur Stromflussrichtung bei direkter elektrischer Widerstandserwärmung metallischer Werkstücke zu erzeugen, wobei die Abhängigkeit des spezifischen elektrischen Widerstandes von der Temperatur zur Beeinflussung der Temperaturverteilung genutzt wird.The invention has for its object to produce a temperature distribution optimally adapted to the end purpose perpendicular to the direction of current flow with direct electrical resistance heating of metallic workpieces, the dependence of the specific electrical resistance on the temperature being used to influence the temperature distribution.

Erfindungsgemäss wird die Aufgabe dadurch gelöst, dass definierte Energieangebote so kurzzeitig auf das metallische Werkstück einwirken, dass innerhalb dieser Zeitabschnitte der zusätzlichen Energieangebote von aussen kein Temperaturausgleich über den Querschnitt des Werkstükkes stattfindet, wodurch sich die Temperaturverteilung im Werkstück senkrecht zur Stromflussrichtung ungleichmässig einstellt.According to the invention, the object is achieved in that defined energy offers act on the metallic workpiece so briefly that there is no temperature compensation over the cross-section of the workpiece within these time periods of the additional energy offers, as a result of which the temperature distribution in the workpiece arises unevenly perpendicular to the direction of current flow.

In weiterer Ausbildung der Erfindung ist es möglich, dass die Zeitabschnitte der zusätzlichen Energieangebote von aussen vor der Einleitung der Widerstandserwärmung des Werkstückes liegen. Diese Zeitabschnitte der zusätzlichen Temperaturbeeinflussung können aber auch innerhalb der Zeitabschnitte der direkten elektrischen Widerstandserwärmung des Werkstücks oder vor und innerhalb der Zeitabschnitte der Widerstandserwärmung liegen. Die zusätzlichen Energieangebote sind nach der Erfindung durch Temperaturzuführung und/oder Temperaturabführung gegeben.In a further embodiment of the invention it is possible that the time periods of the additional energy offers from the outside are before the resistance heating of the workpiece is initiated. However, these periods of additional temperature influence can also lie within the periods of direct electrical resistance heating of the workpiece or before and within the periods of resistance heating. According to the invention, the additional energy offers are provided by temperature supply and / or temperature dissipation.

Beispiel:Example:

Die Erfindung soll an einem Beispiel näher erläutert werden:

  • Ein Stahldraht M 45,0 4 mm und 500 mm Länge, mit einer Ausgangstemperatur von beispielsweise 0°C wird durch Anlegen zweier Kontakte direkt elektrisch widerstandserwärmt.
The invention will be explained in more detail using an example:
  • A steel wire M 45.0 4 mm and 500 mm long, with an initial temperature of 0 ° C, for example, is electrically heated directly by applying two contacts.

Vor Beginn der Stromerwärmung wird durch eine äussere Erwärmungsvorrichtung in Form eines zylindrischen, elektrisch beheizten Hochleistungsofens die Oberflächentemperatur bis in eine Tiefe von 0,5 mm auf 200°C erwärmt. Nach Einschalten der Stromversorgungseinheit für die direkte elektrische Widerstandserwärmung mit einer Spannung von 40 V und einer Einwirkungszeit von 40 s ergibt sich eine Endtemperaturverteilung von 950 °C im ursprünglich wärmeunbeeinflussten Querschnitt und 720 °C in der wärmebeeinflussten Randzone.Before the start of electricity heating, the surface temperature is warmed to a depth of 0.5 mm to 200 ° C by an external heating device in the form of a cylindrical, electrically heated high-performance furnace. After switching on the power supply unit for direct electrical resistance heating with a voltage of 40 V and an exposure time of 40 s, a final temperature distribution of 950 ° C in the originally unaffected cross-section and 720 ° C in the heat-affected edge zone results.

Claims (5)

1. A method for direct electric resistance heating of metallic workpieces where, in addition to this, a temperature influence perpendicularly to the direction of current flow is effected by energy offers from outside within specific periods, characterized in that defined energy offers act for such a short time that no temperature compensation takes place across the section of the workpiece within these periods and, consequently, the temperature distribution perpendicularly to the direction of current flow is non-uniform.
2. A method according to claim 1 characterized in that the periods are within the periods of resistance heating of the workpiece.
3. A method according to claim 1 characterized in that hte periods are within the periods of resistance heating of the workpiece.
4. A method according to claim 1 characterized in that the periods of additional temperature influence are both anterior to and within the periods of resistance heating.
5. A method according to one of claims 1 to 4 characterized in that the energy offers are given by temperature supply and/or dissipation.
EP82100407A 1981-02-02 1982-01-21 Method for the direct electrical resistance heating of metal workpieces Expired EP0057385B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DD227372 1981-02-02
DD81227372A DD160550A3 (en) 1981-02-02 1981-02-02 METHOD FOR THE DIRECT ELECTRICAL RESISTANCE SUPERVISION OF METALLIC WORKPIECES

Publications (3)

Publication Number Publication Date
EP0057385A2 EP0057385A2 (en) 1982-08-11
EP0057385A3 EP0057385A3 (en) 1982-08-18
EP0057385B1 true EP0057385B1 (en) 1986-08-27

Family

ID=5528914

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82100407A Expired EP0057385B1 (en) 1981-02-02 1982-01-21 Method for the direct electrical resistance heating of metal workpieces

Country Status (6)

Country Link
EP (1) EP0057385B1 (en)
AT (1) ATE21799T1 (en)
CS (1) CS247109B1 (en)
DD (1) DD160550A3 (en)
DE (1) DE3272791D1 (en)
SU (1) SU1446170A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0340747A3 (en) * 1988-05-04 1990-06-06 VEB Draht- und Seilwerk Rothenburg Method of and device for improving the coating quality of bar-shaped metallic products
AU3854400A (en) * 1999-06-01 2000-12-18 Mehmet Terziakin Instant heating process with electric current application to the workpiece for high strength metal forming

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1704036A (en) * 1924-11-20 1929-03-05 Electric Furnace Co Annealing furnace

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1448787A (en) * 1964-12-18 1966-03-18 Geoffroy Delore Method and device for continuous annealing of metal wires
DE1583406C3 (en) * 1967-11-15 1974-07-25 Siemens Ag, 1000 Berlin Und 8000 Muenchen Arrangement for the heat treatment of strand material by means of electrical resistance heating
DE2538045A1 (en) * 1975-08-27 1977-03-10 Henrich Kg Multistrand resistance heating plant - for simultaneous annealing of several drawn wires with individual temp. control

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1704036A (en) * 1924-11-20 1929-03-05 Electric Furnace Co Annealing furnace

Also Published As

Publication number Publication date
SU1446170A1 (en) 1988-12-23
CS247109B1 (en) 1986-11-13
DE3272791D1 (en) 1986-10-02
ATE21799T1 (en) 1986-09-15
EP0057385A3 (en) 1982-08-18
EP0057385A2 (en) 1982-08-11
DD160550A3 (en) 1983-09-14

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