EP0062767B1 - Four électrique à arc - Google Patents

Four électrique à arc Download PDF

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Publication number
EP0062767B1
EP0062767B1 EP82101898A EP82101898A EP0062767B1 EP 0062767 B1 EP0062767 B1 EP 0062767B1 EP 82101898 A EP82101898 A EP 82101898A EP 82101898 A EP82101898 A EP 82101898A EP 0062767 B1 EP0062767 B1 EP 0062767B1
Authority
EP
European Patent Office
Prior art keywords
support arm
electrode
electric
arc furnace
vibration
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
EP82101898A
Other languages
German (de)
English (en)
Other versions
EP0062767A1 (fr
Inventor
Erwin Dr. Rer.Nat. Raquet
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.)
Krupp Stahl AG
Original Assignee
Krupp Stahl AG
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
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Application filed by Krupp Stahl AG filed Critical Krupp Stahl AG
Priority to AT82101898T priority Critical patent/ATE15428T1/de
Publication of EP0062767A1 publication Critical patent/EP0062767A1/fr
Application granted granted Critical
Publication of EP0062767B1 publication Critical patent/EP0062767B1/fr
Expired legal-status Critical Current

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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
    • H05B7/00—Heating by electric discharge
    • H05B7/02—Details
    • H05B7/10—Mountings, supports, terminals or arrangements for feeding or guiding electrodes

Definitions

  • the invention relates to an electric arc furnace, in particular for melting steel, with one or more electrodes, each held by a support arm, in which a vibration damper for pitching vibrations is arranged at least on the support arm of the most vulnerable electrode in the support arm / electrode plane , which compensates for the pitching vibrations by vibrations in opposite phases.
  • Such electric arc furnaces are usually equipped with three electrodes and operated as a three-phase furnace.
  • they are equipped with an electrode and operated as a single-phase furnace.
  • a problem which has been known for a long time in such furnaces is that the electrodes break at the clamping point on the support arm.
  • the breakage rate was 5 to 10 breaks per month. After switching to higher melting rates (higher current), the breakage rate increased to 30 to 40 a month.
  • the middle electrode was particularly at risk, i.e. if the electrodes were arranged in a triangle and if the electrodes were held on parallel support arms, the electrode on the middle, shorter support arm.
  • vibration dampers on the electrode arms. These vibration dampers are arranged in such a way that they dampen vibrations occurring perpendicular to the common plane of the electrode and electrode arm.
  • the vibration dampers consist of an inert mass which is held in a middle position by springs and the movement of which is damped by damping means.
  • the inertial mass is arranged in a housing filled with hydraulic fluid, while in another embodiment it is connected to a friction brake.
  • the damping effect is based on the fact that the vibration energy emanating from the support arm / electrode system and transferred to the inertial mass is converted into frictional heat. Such a reduction in the vibrations of the support arm / electrode system is not particularly effective (DE-OS 2 837 741, Fig. 1 and Fig. 2).
  • a vibration damper of the type mentioned at the outset is also known for reducing the breakage rate of electrode breaks.
  • This vibration damper is designed as an active vibration damper in that the pitching vibrations of the electrode are detected by a sensor and evaluated in a regulating and control device that controls a vibrator that mechanically engages the electrode in such a way that its vibrations are in phase opposition to the vibrations of the electrode (DE -OS 2 837 741, Fig. 12).
  • the invention has for its object to provide an electric arc furnace in which the risk of breakage of the electrodes is reduced in a simple manner compared to the conventional arc furnaces.
  • the vibration damper is designed as a vibration system consisting of inert mass and spring, the natural frequency of which is matched to the pitch natural frequency of the vibration system of the support arm / electrode.
  • the vibration damper according to the invention is a passive vibration damper. If its vibration level corresponds to the vibration level of the pitching vibrations of the support arm / electrode system and its natural frequency matches the natural frequency of the support arm / electrode system, the vibration damper is excited to oscillations in phase by the vibrations of the support arm / electrode system.
  • the forces of the inertial mass of the vibration damper built up in the vibration absorber with this excitation counteract the excitation forces of the support arm / electrode system and therefore suppress the excitation forces as they arise so that an oscillation with a large amplitude cannot build up. For this reason, the use of the vibration damper makes it unnecessary to stiffen the support arm construction in particular and / or to manufacture the electrodes from a mechanically more resistant material.
  • the low load due to the vibrations also leads to a reduced load on the drive and the guidance of the support arm construction.
  • the fracture rate can already be reduced considerably if a vibration damper is only arranged on the middle support arm.
  • the electrode of the middle support arm is particularly at risk because the vibrations of the electrode lie in the plane of the electrode and the support arm, i.e. in a plane in which the construction is relatively stiff, while the vibrations of the outer electrodes, whose plane of vibration does not match that Level of the electrodes and the support arms coincides, can be partially absorbed by torsion of the support arms.
  • the spring of the vibration damper is parallel to a damper that widens the resonance.
  • the damper only has the purpose of flattening the resonance point of the vibration damper so that the Ab adjustment of the vibration damper to the support arm / electrode system requires no great care.
  • a particularly compact vibration damper is characterized in that the inertial mass has a pin which is guided in a stationary sleeve, on the outside of which the spring designed as a helical spring is guided.
  • the inert mass can be cup-shaped and enclose the spring.
  • the inertial mass of the vibration absorber preferably carries a vibration pickup which, when a predeterminable amplitude value of the vibrations of the inertial mass is exceeded, gives a switch-off signal to the power supply to the electrode or electrodes. Switching off the power supply also counteracts the build-up of vibrations.
  • the inertial mass of the vibration damper can additionally form the armature of an electromagnet, the coil of which is controlled in dependence on the control signal of a vibration sensor for the pitching vibrations of the vibration system support arm / electrode in the support arm / electrode level such that the as a result, vibration absorbers on the support arm excited to vibrations in the plane of the support arm / electrode build up forces which counteract the excitation forces of the arc which are effective at the lower end of the electrode.
  • the vibration sensor can be arranged on the inertial mass.
  • the arc furnace 1 shown in FIGS. 1 and 2 is closed by a cover 2 in which three openings 3, 4, 5 are provided for electrodes 6, 7, 8 arranged vertically downwards, parallel to one another and at the corner points of an equilateral triangle .
  • a support arm 9, 10, 11 is assigned to each electrode 6 to 8.
  • the support arms 9 to 11 run parallel to each other.
  • the two outer support arms 10, 11 are of equal length and longer than the middle support arm 9. All of the support arms 9 to 11 are each held on a stand 12 which is adjustable in height. This height adjustability makes it possible to change the distance of the electrode ends from the bath level 13.
  • a vibration damper 14, 15, 16 is coupled to the free ends of the support arms 9 to 11.
  • the vibration damper has a rotationally symmetrical structure.
  • the vibration absorber shown in Fig. 3 consists of a circular cylindrical pot 17, a central pin 18, a pin 18 and pot 17 crosshead 19 connecting parts 17 to 19 form the so-called "inert" mass of the vibration absorber, a fixed guide sleeve 20 for the pin 18, a helical spring 21 arranged on the outside on the guide sleeve 20 in the annular gap between the pin 18 and the pot 17, and the end face of the pot 17 and the pin 18 on a support 22 coupling damping body 23, 24.
  • the entire unit is encapsulated in a housing 25.
  • the parts forming the inertial mass of the vibration absorber (hollow cylindrical pot 17, pin 18, crosshead 19) and the spring 21 are tuned in their natural frequency to the natural frequency of the oscillating system consisting of support arm 9 to 11 and electrode 6 to 8.
  • a vibration sensor 26, 27 can be provided on the inertial mass 17 to 19 of the vibration absorber 14 to 16 or the support arms 9 to 11, which controls the current to be supplied to the electrodes 6 to 8 via a control device in such a way that when a predeterminable maximum value is exceeded, the Power supply for one or more phases is interrupted. This current interruption dampens the system.
  • an active vibration absorber or, instead of the purely passive vibration absorber described above, a combination of passive and active vibration absorbers according to FIG. 4 can be provided.
  • the basic structure of such a vibration damper corresponds to that of the passive vibration damper, as a comparison of FIGS. 3 and 4 shows.
  • the active vibration damper has an electromagnet, the armature of which is formed by at least part of the inertial mass, in the exemplary embodiment the hollow cylindrical part 17.
  • This hollow cylindrical part 17 is surrounded by an electrical coil 28 which is arranged on a stationary guide sleeve 30.
  • the power supply to the coil 28 is controlled by a control device, not shown.
  • the control device receives a control signal from a vibration sensor 29 which is arranged on the inertial mass 17 to 19.
  • the control is thus carried out as a function of the vibrations picked up by the vibration sensor 29 in such a way that the vibration damper is excited to vibrate in such a way that the spring 21 and the damping bodies 23, 24 Forces on the support arm 9 to 11 are built up, which counteract the excitation forces at the lower end of the electrodes 6 to 8 by the arc.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)

Claims (10)

1. Four électrique à chauffage direct par l'arc, en particulier pour fondre de l'acier, avec une ou plusieurs électrodes (6-8) portées respectivement par un bras-support, dans lequel est prévu, au moins sur le bras-support (9) de l'électrode (6) présentant le plus grand risque de supture, un amortisseur de vibrations (14) pour les vibrations de tangage dans le plan bras-support/électrode (9/6), qui compense les vibrations de tangage par des vibrations en opposition de phase, caractérisé par le fait que l'amortisseur de vibrations est formé par un système oscillant constitué par une masse inerte (17-19) et un ressort (21), dont la fréquence propre est ajustée à la fréquence propre de tangage du système oscillant bras-support/électrode (9/6).
2. Four à chauffage direct par l'arc selon la revendication 1, avec trois électrodes disposées en triangle, maintenues par des bras-supports parallèles les uns sous les autres, parmi lesquels les bras-supports extérieurs ont la même longueur et le bras-support moyen a une longueur différente, caractérisé par le fait que l'amortisseur de vibrations (14) est disposé sur le bras médian (9).
3. Four à chauffage direct par l'arc selon la revendication 1 ou 2, caractérisé par le fait que chaque amortisseur de vibrations (14, 15, 16) est disposé sous un capot de protection (25).
4. Four à chauffage direct par l'arc selon l'une des revendications 1 à 3, caractérisé par le fait qu'un amortisseur (23, 24) élargissant la résonance est disposé parallèle au ressort (21) de l'amortisseur de vibrations (23, 24).
5. Four à chauffage direct par l'arc selon la revendication 4, caractérisé par le fait que la masse inerte (17-19) présente un tenon (18) qui est guidé dans une douille fixe (20) sur la face extérieure de laquelle le ressort (21), construit sous la forme d'un ressort hélicoïdal, est guidé.
6. Four à chauffage direct par l'arc selon la revendication 4 ou 5, caractérisé par le fait que la masse inerte (17-19) a la forme d'un pot et entoure le ressort (21).
7. Four à chauffage direct par l'arc selon l'une des revendications 1 à 3, caractérisé par le fait qu'un absorbeur de vibrations (26, 27) avec un émetteur de signal de position est adjoint au système bras-support/électrode (9-11/6-8) qui, en cas de dépassement d'une valeur d'amplitude prédéterminée, donne à l'alimentation en courant un signal d'interruption pour une ou plusieurs phases.
8. Four à chauffage direct par l'arc selon la revendication 7, caractérisé par le fait que la masse inerte (17, 18, 19) de l'amortisseur de vibrations (14,15, 16) porte l'absorbeur de vibrations (26).
9. Four à chauffage direct par l'arc selon la revendication 1, caractérisé par le fait que la masse inerte (17, 18, 19) de l'amortisseur de vibrations (14) forme l'induit d'un électro-aimant dont la bobine (28) est commandée, en fonction du signal de position d'un absorbeur de vibrations (29) pour les vibrations de tangage du système vibrant bras-support/électrode (9/6) dans le plan bras-support/électrode (9/6) de telle manière que l'amortisseur de vibrations (14) ainsi entraîné en vibrations dans le plan bras-support/électrode (9/6) produise dans le bras-support (9) des forces qui s'opposent aux forces d'excitation de l'arc électrique agissant à l'extrémité inférieure de l'électrode (6).
10. Four à chauffage direct par l'arc selon la revendication 9, caractérisé par le fait que l'absorbeur de vibrations (29) est disposé sur la masse inerte (17-19).
EP82101898A 1981-04-08 1982-03-10 Four électrique à arc Expired EP0062767B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82101898T ATE15428T1 (de) 1981-04-08 1982-03-10 Elektrischer lichtbogenofen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3114145A DE3114145C2 (de) 1981-04-08 1981-04-08 Elektrischer Lichtbogenofen
DE3114145 1981-04-08

Publications (2)

Publication Number Publication Date
EP0062767A1 EP0062767A1 (fr) 1982-10-20
EP0062767B1 true EP0062767B1 (fr) 1985-09-04

Family

ID=6129657

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82101898A Expired EP0062767B1 (fr) 1981-04-08 1982-03-10 Four électrique à arc

Country Status (4)

Country Link
EP (1) EP0062767B1 (fr)
JP (1) JPS57176689A (fr)
AT (1) ATE15428T1 (fr)
DE (2) DE3114145C2 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3413033A1 (de) * 1984-04-04 1985-10-17 Mannesmann AG, 4000 Düsseldorf Verfahren und anordnung einer oszillierenden elektrode
US5297160A (en) * 1992-01-10 1994-03-22 Mannesmann Aktiengesellschaft Furnace electrode design

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH380354A (de) * 1960-05-06 1964-07-31 Sulzer Ag Schlankes Bauwerk
US3207014A (en) * 1962-09-24 1965-09-21 Kennametal Inc Method and apparatus for damping vibrations
DE1918747A1 (de) * 1969-04-14 1970-10-15 Messerschmitt Boelkow Blohm Schwingungsreduktion durch Anti-Schwinger
US3911199A (en) * 1974-04-26 1975-10-07 Westinghouse Electric Corp Seismic motion-damper for upstanding electrical equipment
DE2605476A1 (de) * 1976-02-12 1977-08-18 Johann Prof Dr I Kleinwaechter Aktive schwingungsdaempfung elastischer antriebselemente
DE2837741A1 (de) * 1978-08-21 1980-03-06 Bbc Brown Boveri & Cie Vorrichtung zur verbesserung der taetigkeit eines lichtbogenofens

Also Published As

Publication number Publication date
DE3114145C2 (de) 1985-04-04
EP0062767A1 (fr) 1982-10-20
ATE15428T1 (de) 1985-09-15
DE3265954D1 (en) 1985-10-10
JPS57176689A (en) 1982-10-30
DE3114145A1 (de) 1982-10-28

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