EP0062767A1 - Four électrique à arc - Google Patents

Four électrique à arc Download PDF

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Publication number
EP0062767A1
EP0062767A1 EP82101898A EP82101898A EP0062767A1 EP 0062767 A1 EP0062767 A1 EP 0062767A1 EP 82101898 A EP82101898 A EP 82101898A EP 82101898 A EP82101898 A EP 82101898A EP 0062767 A1 EP0062767 A1 EP 0062767A1
Authority
EP
European Patent Office
Prior art keywords
support arm
electrode
vibration
arc furnace
vibrations
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
EP82101898A
Other languages
German (de)
English (en)
Other versions
EP0062767B1 (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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=6129657&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0062767(A1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
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.
  • 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, ie if the electrodes were arranged in the Triangle and if the electrodes are held on parallel support arms, the electrode on the middle, shorter support arm.
  • vibration dampers on the electrode arms. These vibration dampers are arranged such that they dampen vibrations occurring perpendicular to the common plane of the electrode and the 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).
  • the invention has for its object to provide an electric arc furnace in which the risk of breakage of the electrodes is reduced compared to the conventional arc furnace.
  • At least one vibration absorber is arranged on the support arm of the most risk of fracture electrode, which in its natural frequency to the natural frequency of the vibration system support arm / electrode for the pitch: - vibrations in the plane of the support arm / electrode is tuned.
  • the vibration absorber is arranged on the middle support arm.
  • the invention is based on the knowledge that the electrode and support arm as a system vibrate in such a way that pitch vibrations of the support arm with the electrode occur in the support arm / electrode plane. These vibrations are fanned by arc vibrations (so-called flickering vibrations).
  • the electrode acts like a lever arm on the support arm and is most subject to bending at its clamping point.
  • a vibration damper By attaching a vibration damper to the support arm, the natural vibrations are damped in such a way that the vibration amplitude is considerably reduced.
  • the use of the vibration damper makes it unnecessary to stiffen the construction and the drive of the support arm construction or to manufacture the electrodes from a mechanically better material.
  • the reduction in the vibration amplitude of the support arm / electrode system also leads to a reduced load on the drive and the guidance of the support arm construction and the support arm construction itself.
  • the vibrations are reduced particularly effectively because the reduction is not based on a conversion of kinetic energy into thermal energy, but rather on the fact that the vibration damper is excited to vibrations which correspond to the vibrations of the support arm / electrode system, but are opposed to it .
  • This antiphase of the vibrations means that the exciting vibrations are suppressed by the excited vibrations as they arise. Large amplitudes cannot therefore develop.
  • 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 rigid, so that the vibrations of the outer electrodes, whose plane of vibration is not in line with the plane the electrodes and the support arms coincide, can be partially absorbed by torsion of the support arms.
  • Passive and active vibration dampers are suitable as vibration dampers, but also combinations of passive and active vibration dampers.
  • a passive vibration damper preferably consists of a spring, a damper lying parallel to it and an inertial mass carried by the spring and the damper. Since the reduction of the vibrations of the support arm / electrode system is not based on a damping effect, i.e. conversion of the kinetic energy into heat, but on the fact that the stimulating forces build up opposing forces in the vibration absorber, the vibration absorber does not rely on a damper.
  • the damper has only the purpose of flattening the resonance point of the vibration absorber, so that the adjustment of the vibration absorber 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 forms the armature of an electromagnet in an active vibration damper, the coil of which is controlled in dependence on the control signal of a vibration sensor for pitching vibrations of the support arm / electrode system in the support arm / electrode plane such that the vibration absorber thereby excited to vibrate in the plane of the support arm / electrode builds up forces on the support arm 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 support arm, in particular on the inertial mass.
  • Such a vibration damper allows damping of the vibrations of the vibration system over a wider frequency range and with greater effectiveness than passive vibration dampers.
  • the characteristics of the passive vibration damper will also be realized in an active vibration damper in order to keep the magnetic forces as small as possible.
  • the supply of the current to the electrode or electrodes can be interrupted for one or more current phases by means of a vibration sensor when a certain amplitude value of the vibrations is exceeded.
  • 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 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 arms 9 to 11 and electrodes 6 to 8.
  • a vibration sensor 26, 27 can be provided, which controls the current to be supplied to the electrodes 6 to 8 via a control device such 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 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 takes place in dependence on 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 forces are built up on the support arm 9 to 11 via the spring 21 and the damping bodies 23, 24, which the excitation forces at the lower end of the electrodes Counteract 6 to 8 by the arc.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Furnace Details (AREA)
  • Vertical, Hearth, Or Arc Furnaces (AREA)
  • Discharge Heating (AREA)
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 true EP0062767A1 (fr) 1982-10-20
EP0062767B1 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)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT409058B (de) * 1992-01-10 2002-05-27 Mannesmann Ag Dreiphasiger lichtbogenofen

Families Citing this family (1)

* 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

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB950983A (en) * 1960-05-06 1964-03-04 Sulzer Ag Damping vibrations in chimneys, towers, or masts
DE1918747A1 (de) * 1969-04-14 1970-10-15 Messerschmitt Boelkow Blohm Schwingungsreduktion durch Anti-Schwinger
DE1303885B (fr) * 1962-09-24 1973-09-13
DE2605476A1 (de) * 1976-02-12 1977-08-18 Johann Prof Dr I Kleinwaechter Aktive schwingungsdaempfung elastischer antriebselemente
GB1509223A (en) * 1974-04-26 1978-05-04 Westinghouse Electric Corp Seismic motion-damper for upstanding electrical equipment
DE2837741A1 (de) * 1978-08-21 1980-03-06 Bbc Brown Boveri & Cie Vorrichtung zur verbesserung der taetigkeit eines lichtbogenofens

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB950983A (en) * 1960-05-06 1964-03-04 Sulzer Ag Damping vibrations in chimneys, towers, or masts
DE1303885B (fr) * 1962-09-24 1973-09-13
DE1918747A1 (de) * 1969-04-14 1970-10-15 Messerschmitt Boelkow Blohm Schwingungsreduktion durch Anti-Schwinger
GB1509223A (en) * 1974-04-26 1978-05-04 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

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT409058B (de) * 1992-01-10 2002-05-27 Mannesmann Ag Dreiphasiger lichtbogenofen

Also Published As

Publication number Publication date
DE3114145C2 (de) 1985-04-04
ATE15428T1 (de) 1985-09-15
EP0062767B1 (fr) 1985-09-04
DE3265954D1 (en) 1985-10-10
JPS57176689A (en) 1982-10-30
DE3114145A1 (de) 1982-10-28

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