JPH0447919Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an arc heating furnace that heats molten metal by generating an arc between a plurality of electrodes and molten metal, like a ladle refining furnace. More specifically, the present invention relates to the electrode lifting mechanism, its control device, a device for aligning the electrodes, and a power supply circuit to the electrodes.

[Conventional technology]

FIG. 3 is a perspective view of a conventional three-phase AC ladle refining furnace. In the figure, 1, 1a, 1b are electrodes, 2,
2a, 2b are arcs, 3 is molten metal, 4, 4a,
4b is an electrode support arm mast that moves up and down,
Reference numerals 5, 5a, and 5b are electrode lifting/lowering drive devices comprising a motor and pulleys, 6, 6a, and 6b are electrode lifting/lowering control devices, and 20 is a ladle.

Next, this operation will be explained. Electrodes 1, 1a, 1b each move up and down independently to raise and control the temperature of the molten metal 3 in the ladle 20.
An arc 2, 2a, 2b is formed between the molten metal 3 and the molten metal 3.
This is done by generating.

The electrodes 1, 1a, 1b are moved individually by electrode lifting/lowering drive devices 5, 5a, 5b which move electrode supporting arm masts 4, 4a, 4b up and down via pulleys. Further, these electrode lifting/lowering drive devices 5, 5a,
5b is controlled by electrode elevation control devices 6, 6a, and 6b.

In this figure, the power supply circuit that supplies power to the electrodes 1, 1a, and 1b is not shown.

FIG. 4 is a system diagram showing a part of the conventional three-phase AC ladle refining furnace shown in FIG. In the figure, 1, 2, 3, 4, 5, 6 are the same as in Figure 3, 7
A current is supplied to the electrode 1, and cooling water is passed through the electrode. A water-cooled copper tube, 10 is a support supporting the water-cooled copper tube 7, and 8 is a water-cooled cable interposed between the transformer 9 and the water-cooled copper tube 7.

In the conventional electric arc furnace configured in this manner, three sets of electrode lifting/lowering drive devices 5, 5a, 5b and electrode control devices 6, 6a, 6b are required. Further, since the three electrodes 1, 1a, and 1b move separately and independently, the water-cooled cable 8 and water-cooled copper tube 7 that feed power to each electrode are arranged so as not to come into contact with each other. However, for this reason, these power supply circuits are not integrated.

In the case of an arc furnace for scrap melting, the arc 2 is connected to the electrode 1 and the scrap (not shown).
However, in a refining furnace, arc 2 occurs between molten metal 3 and electrode 1, so there is no difference between each electrode. , Arc 2 is also stable.

[Problem that the invention attempts to solve]

In the conventional arc heating furnace as mentioned above,
Although the arc furnace for scrap melting is different and the arc is stable and the difference in arc between each electrode is small, each electrode was controlled and operated individually, so (1) the structure and control system could be tampered with. The equipment is complicated and the equipment cost is high.

(2) Because the arrangement of the conductor that supplies power to the electrodes is restricted, the impedance of the furnace becomes unbalanced, and impedance cannot be reduced. For this reason, it is not possible to generate the same arc on each electrode,
The power factor is also getting worse.

(3) In terms of control, so-called constant impedance control is usually performed to keep the ratio of the voltage between the molten steel and the electrode and the arc current constant for each electrode. However, at this time, if the arc length changes due to waves generated on the surface of the molten steel, tracking of such fast-changing disturbances is insufficient, and hunting tends to occur. In addition, there was a problem in that disturbances in control at one pole affected other poles, resulting in poor control results.

[Means for solving problems]

In the arc heating furnace according to this invention, in an arc heating furnace that generates an arc between a plurality of electrodes and molten metal, a device for aligning the ends of the plurality of electrodes on one plane, and a device for aligning the ends of the plurality of electrodes in a single plane. An electrode support arm mast that can be gripped, an electrode lift drive device that moves the electrode support arm mast up and down, an electrode lift control device that controls this electrode lift drive device, and a transformer and water-cooled cable that supplies power to the electrodes. It is constructed.

[Effect]

In this invention, when an electrode support arm mast that collectively holds a plurality of electrodes goes up and down, the electrodes go up and down simultaneously. The electrode elevating and lowering drive device controlled by the electrode elevating and lowering control device converts power into vertical movement of the electrode support arm mast via a pulley. If the electrodes are lowered onto a flat plate placed next to the ladle to align the electrode ends, the electrodes will line up on one plane.If the conductor wires are spaced and their lengths are approximately equal, the impedance between the multiple electrodes will be approximately equal. be equal. Also, the power factor decreases.

〔Example〕

FIG. 1 is a perspective view of an embodiment of this invention.
In the figure, 1, 2, 3, 5, 6 are the same as those shown in Figure 3, and 4c is the three electrodes 1, 1a, 1b.
This is an electrode support arm mast that raises and lowers at the same time.

In this invention, three electrodes 1, 1a, 1b are used.
Since the electrodes are raised and lowered all at once, only one set of the electrode raising/lowering driving device 5 is required.

Further, since the amount of wear of each electrode 1 to 1b during operation is different, a mechanism is provided to align the positions of the electrode tips. This can be easily done, for example, by loosening the grip on the electrodes 1 to 1b, placing them on a flat plate (not shown) provided near the ladle 3, and then gripping them again.

Furthermore, the arc during operation can be controlled by comparing the input power of the three phases with the average value of the three-phase current, or if the consumption speed of the electrodes 1 to 1b is known, it is possible to control the arc between the electrodes 1 to 1b and the molten steel 3. After adjusting the spacing to a predetermined spacing, the electrodes 1-1b may be pulled down to compensate for the amount of wear.

In this embodiment, the electrode supporting arm mast 4c and the electrode lifting/lowering drive device 5 are all provided in one unit, but this may not necessarily be advantageous in the case of a large furnace. However, only one electrode elevation control device 6 is used for collective control.

Next, in the electrode lifting mechanism described above, since the three electrodes move up and down or rotate at once, each electrode 1 to 1b
Conductors such as water-cooled cables that feed power can be freely arranged.

FIGS. 2a and 2b are explanatory diagrams of the device according to this invention. Figure a is an explanatory diagram showing how the water-cooled copper tubes 7 and water-cooled cables 8 are arranged in parallel, and Figure b is an explanatory diagram showing the relationship between the arrangement of the water-cooled copper tubes 7 and the electrode support arm mast.

It can be understood from the above diagram a that the impedance of the conductor is balanced, small, and the conducting wire is short, so that the induction loss is also reduced.

As shown in b, the three-phase conductors are arranged symmetrically, and the transformer 9 is connected to the electrode 1 by the shortest possible path. and,
A large distance 30 is provided from the steel electrode support arm mast 4 to reduce induced current.

By making the three-phase conductors symmetrical in this way, the impedance unbalance of the circuit can be eliminated, the power supply to each electrode 1, 1a, and 1b can be balanced, and the heat load in the furnace can be equalized. is measured.

Furthermore, since the shortest path can be selected and the three-phase conductors can be arranged close to each other, impedance can be reduced. At the same time, the magnetic fields created by the three-phase conductors cancel each other out, which has the effect of reducing losses due to induced currents generated in the electrode support arm mast and the like.

[Effect of idea]

As explained above, this invention combines the electrode lifting and lowering drive and control device into one set, which simplifies the equipment configuration and is excellent in terms of maintainability and economy.

Since the electrode elevation control device for a plurality of electrodes is common, there is no interference between the control devices for each electrode as in the conventional case, and stable control is possible.

Since the arrangement of the power supply conductors to each electrode can be freely selected, the impedance of each conductor can be made equal, and as a result, the electric circuit can be balanced, the heat load in the furnace can be equalized, and efficiency can be increased.

Similarly, by carefully arranging the conductors, the impedance of the conductors can be lowered, and as a result, the operating power factor of the furnace can be increased. At the same time, loss due to electromagnetic induction can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of one embodiment of this invention, Fig. 2 a and b are explanatory diagrams of other embodiments of this invention, Fig. a is an explanatory diagram of a water-cooled cable, etc., and Fig. b is a water-cooled copper tube and an electrode. FIG. 3 is a perspective view of a conventional arc heating furnace, and FIG. 4 is a partial system diagram of a conventional three-phase AC ladle refining furnace. In the figure, 1 is an electrode, 2 is an arc, 3 is a molten metal, 4 is an electrode support arm mast, 5 is an electrode lift drive device, 6 is an electrode lift control device, 7 is a water-cooled copper tube, 8 is a water-cooled cable, and 9 is a water-cooled cable. A transformer, 10 is a support, 20 is a ladle, and 30 is a distance. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] In an arc heating furnace that generates an arc between a plurality of electrodes and molten metal, a device for aligning the ends of the plurality of electrodes on one plane, an electrode support arm mast capable of holding the electrodes all at once, and the electrodes. An arc heating device comprising: an electrode lift drive device that moves the support arm mast up and down; an electrode lift control device that controls the electrode lift drive device; a transformer and water cooling cable that supply power to the electrodes; Furnace.