JPH10134957A - Electrode support beam and electrod elevating mast for electric arc furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the electrode support beam and the electrod elevating mast for an electric arc furnace lighter in weight, and materialize capacity reduction of a drive motor, or enhancement on response concerning the elevating control of each electrode. SOLUTION: The entire weight is made lighter by letting the frame structure body of the electrode supporting beam 3b' be formed out of the piled-up plate of a copper plate and an aluminum alloy plate while its electric resistance is reduced. The electrode elevating mast 7b' is also made lighter to a great extent by letting its frame structure body be formed out of an aluminum alloy while its mechanical strength is maintained. Since no electromagnetic induction heating takes place because an aluminum alloy is non-magnetic, it is not necessary that a top board 8b is formed into a water cooling structure. Furthermore, steel plates 24 are joined to the respective abutting faces of the electrode elevating mast 7b' with guide rollers 10b so as to allow the occurrence of abrasion on each abutting face to be prevented, and when it is worn, it is enough to replace only a worn steel plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode support beam and an electrode lifting mast in a three-phase AC or DC electric arc furnace, while reducing the electric resistance of the electrode support beam used as a large current conductor. The present invention also relates to an improvement to reduce the weight and to reduce the weight of an electrode lifting mast and to facilitate maintainability.

[0002]

2. Description of the Related Art In general, an electric arc furnace has three graphite electrodes in a three-phase AC system and one electrode in a DC system.
This graphite electrode is inserted into a furnace, an arc is generated between a material such as scrap iron previously charged into the furnace and the electrode to melt the material and heat the molten steel. . When the melting step and the refining step are performed separately, an arc furnace for steelmaking and an arc furnace for refining are provided for each step, but the former is a three-phase AC or DC arc furnace, and the latter is a three-phase arc furnace. A phase-change arc furnace is applied.

In an electric arc furnace, it is necessary to control the amount of the graphite electrode inserted into the furnace in order to control the temperature of the furnace. An electrode holder for holding the electrode and an electrode integrally formed with the electrode holder are required. A support beam, an electrode lifting mast for supporting the electrode support beam, and a lifting drive device thereof are indispensable. Here, taking as an example an electrode lifting / lowering system applied to a three-phase AC arc furnace, the electrode holder and the electrode support beam are arranged in a plane as shown in FIG. FIG. 6 shows a system configuration of an electrode lifting mast relating to the support beam and a lifting drive device thereof.

In FIG. 5, reference numerals 1a to 1c denote electrodes inserted into the furnace, 2a to 2c denote electrode holders for holding the electrodes 1a to 1c, and 3a to 3c.
3c indicates an electrode support beam, and 4a to 4c indicate terminals. FIG. 6 is a side view of the electrode 1b and the electrode holder 2 in FIG.
b and the electrode support beam 3b (the center set), an electrode lifting mast and its lifting drive are shown, but the basic configuration is the same for the other sets. The configuration according to the above will be described. 5b is a flexible cable connecting the terminal 4b and a furnace transformer (not shown), 6b is an insulating plate, 7b is an electrode lifting mast, 8b is an electrode lifting mast 7b top plate, and 9b is an electrode lifting and lowering. The lifting sheave 10b attached to the lower end of the mast 7b is a guide roller that rotates while abutting on a side wall thereof to support the electrode mast 7b from the side (a total of 16; 11b is a lift control unit having a built-in motor, 12b is a drum rotated by the motor of the lift control unit 11b, and 13b is a fixed end. It is a wire rope that supports the groove of the lifting sheave 9b from below while being suspended between the winding part of the drum 12b. When a large current is applied, the electrode holder 2b and the electrode support beam 3b generate heat due to their internal resistance, and a flame or gas blown up from the furnace, and further, the red-hot electrode 1b
Is heated by the radiant heat from the nozzle, a cooling water flow passage is formed inside the cooling water passage, and water is supplied from the port 14b to bypass the water passage inside the electrode support beam 3b and the electrode holder 2b so as to bypass the port 15b. It is to be collected from.

[0005] Based on the above configuration, in the electric arc furnace,
The elevation control unit 11b adjusts the winding amount of the wire rope 13b by the drum 12b by rotating the built-in motor adaptively based on the current / voltage detection data of the furnace, thereby moving the electrode elevation mast 7b vertically. By moving it, the amount of insertion of the electrode 1b into the furnace is controlled.

[0006]

As shown in FIG. 7A, which is a cross-sectional view taken along the line BB of FIG. 6, the above-mentioned electrode support beam 3b is formed into a frame-like structure having a vertical rectangular shape. Conventionally, it is configured as a welded structure of an aluminum alloy plate or a structure formed by a superposed plate of a copper plate and a steel plate as disclosed in Japanese Utility Model Registration No. 7-19997 (U.S. Patent No. 2502823). . Note that reference numeral 16b in FIG. 7A denotes a partition plate for forming a bypass flow path for cooling water.

[0007] However, when the entire structure is made of a frame-shaped structure made of an aluminum alloy plate, it is advantageous in reducing the weight of the electrode support beam 3b, but the aluminum alloy has a higher specific electric resistance than copper. Therefore, there is a problem that the effective power is reduced. In particular, in the three-phase alternating current system, the tendency becomes remarkable because the current flows only in the surface layer portion due to the skin effect. On the other hand, in the case of a frame-shaped structure made of a superposed plate of a copper plate and a steel plate, it is possible to suppress the electric resistance to a small value because the copper plate having a small specific electric resistance becomes a large current conductor, but it is used as a strength member. The weight of the steel plate is large, and it is difficult to reduce the weight of the electrode support beam 3b. That is, the electrode support beam has a reduced electric resistance to suppress power loss and a reduced total weight to reduce the capacity of the motor of the elevation control unit 11b, or to increase the elevation speed to increase the control responsiveness. However, none of the frame-like structures relating to the electrode support beams 3b satisfy the requirements under contradictory conditions.

On the other hand, the electrode lifting mast 7b also has a square frame as shown in FIG. 7B, which is a sectional view taken along the line CC in FIG. It is configured as a welded structure with steel plates to obtain.

However, as shown in FIG. 6, it is necessary to secure the required stroke of the electrode lifting / lowering mast 7b and to maintain a reliable stroke without blur by the guide rollers 10b provided above and below. Its overall length is considerably longer. Therefore, the electrode lifting mast 7b formed of a steel plate structure has a large total weight, and the lifting control unit 11b
Therefore, the capacity of the motor needs to be increased, and the responsiveness of the elevation control deteriorates. Also, the top plate 8b of the electrode lifting mast 7b
If a steel plate is applied, the top plate 8b must have a water-cooled structure as shown in FIG. 6 because it is subjected to electromagnetic induction heating due to a large current flowing through the electrode support beam 3b. This will increase the number of water leakage accidents. Further, during operation of the electric arc furnace, the guide roller 10b supports the side wall of the electrode elevating mast 7b while abutting and rotating, but it is not easy to repair when the abutting surface is worn. However, there is a disadvantage that the entire electrode lifting mast 7b must be replaced.

In view of the above, the present invention has been devised of a material and a structure applied to the electrode support beam and the electrode lifting mast to provide those components which have solved the above-mentioned problems, and have excellent operation efficiency. It was created with the aim of configuring an electric arc furnace system that has easy maintenance.

[0011]

According to a first aspect of the present invention, there is provided an electric arc furnace having an electrode supporting beam, wherein a frame-like structure of the electrode supporting beam is formed of a superposed plate of a copper plate and an aluminum alloy plate. Related to the electrode support beam.

In the electrode supporting beam of the present invention, the copper plate mainly serves as a conductor member, and the aluminum alloy plate mainly serves as a strength member. The copper plate is the most advantageous material for the conductor, and can be made thinner than when only the aluminum alloy plate is applied to the conductor. In addition, aluminum alloys have properties superior to steel plates in terms of strength per unit weight, which is advantageous in reducing the weight while increasing the strength. Even if it secures, weight reduction can be achieved as compared with the case where a superposed plate of a copper plate and a steel plate is applied as in the conventional case.

According to a second aspect of the present invention, in a mast for raising and lowering an electrode of an electric arc furnace, a frame-like structure of the mast is made of an aluminum alloy, and a contact surface with a guide roller for guiding while supporting the mast for raising and lowering the electrode is provided. The present invention relates to a mast for elevating and lowering electrodes of an electric arc furnace, wherein steel plates are joined by welding.

In the electrode lifting mast of the present invention, the frame-shaped structure as the main body is made of an aluminum alloy to reduce the total weight, and the aluminum alloy is inferior in wear resistance. A steel plate with excellent wear resistance is separately joined to the surface to prevent wear. Since the steel plate is a separate member from the main body, it can be easily replaced or repaired even when it is worn, and it is not necessary to replace the entire main body. In addition, the contact surface with the guide roller is the longitudinal direction of the frame-shaped structure,
The steel plate also functions as a reinforcing member for the frame-shaped structure that is the main body.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrode supporting beam and an electrode lifting mast of an electric arc furnace according to the present invention will be described in detail with reference to FIGS. First, FIG. 1 corresponds to the electrode lifting / lowering system of FIG. 6, and shows an overall configuration when the electrode supporting beam and the electrode lifting / mast of this embodiment are applied. Therefore, in FIG. 1, each element indicated by the same reference numeral as FIG. 6 corresponds to the same element, and the description thereof will be omitted here.

The feature of the electrode lifting system according to this embodiment lies in the structure of the electrode support beam 3b ', the electrode lifting mast 7b', and the top plate 8b '. First, with respect to the electrode support beam 3 ', a cross section taken along the line DD is shown in FIG. 2, and the frame-like structure is composed of a superposed plate of a copper plate 21 and an aluminum alloy plate 22. Specifically, the welded structure of the superposed plate is configured in such a manner that the pure copper plate 21 is on the outer side and the aluminum alloy plate 22 (material: 5056-H38) is on the inner side.

Here, the electrode support beam 3 'according to this embodiment
Compared with an electrode supporting beam consisting of a frame-like structure of only the aluminum alloy (5056-H38) according to the prior art and an electrode supporting beam consisting of a frame-like structure of a superposed plate of a pure copper copper plate and a steel plate (SS400). View. First, a comparison is made with the above [electrode support beam made of only aluminum alloy]. The conductivity of pure copper (102%) is about 3.5 times that of aluminum alloy (29%), and the specific gravity of copper (8.89) is specific gravity of aluminum alloy (2.90%).
64), which is about 3.4 times that of copper and aluminum alloys, the weights having the same length and the same resistance value are almost the same for copper and aluminum alloys. However, this is the case of direct current, and in the case of alternating current, the current flows only to the surface layer of the conductor due to the skin effect.Therefore, the conductivity of aluminum alloy is small, so the frame shape of the cross section is larger than that of copper. Without a structure, the electrical resistance cannot be the same as copper. That is, in order to obtain an electric resistance equivalent to that of the electrode support beam 3 'of this embodiment using an electrode support beam made only of an aluminum alloy, it is necessary to make its cross-sectional dimension considerably larger than that of this embodiment.
Therefore, in terms of the total weight, the electrode support beam 3 ′ of this embodiment is
Can be made lighter than an electrode support beam made only of an aluminum alloy.

Next, a comparison will be made with [Electrode support beam formed by a superposed plate of a copper plate and a steel plate]. Electrode support beam 3 'of this embodiment
Are common in that a copper plate is used as the conductive member. By the way, steel has a specific gravity of 7.85 and a yield point of 255 (N / mm ² ). Therefore, the strength per unit weight is 255 / 7.85 = 31.2 (N / mm ² ). Become. On the other hand, aluminum alloy (5056-H38) has a specific gravity of 2.64 and a yield point of 345 (N / mm ² ) as described above.
The strength per unit weight is 345 / 2.64 = 131 (N / mm
² ) Therefore, comparing the strength per unit weight of the two, the aluminum alloy has 4.2 times the strength of steel. That is, when a structure having the same basic structure and the same strength is manufactured, the weight of the aluminum alloy is 1 / 4.2 = about 24% of steel.
As a result, the structure of the electrode support beam 3 ′ of this embodiment can significantly reduce the total weight while having the same electrical resistance and strength as those of the electrode support beam made of a superposed plate of a copper plate and a steel plate.

Turning now to the electrode lifting mast 7b ', its EE section is shown in FIG. 3, and the frame-like structure 23 is made of an aluminum alloy (5056-H38).
Steel plate (8 pieces) 2 on each contact surface of the surface with guide roller 10b
4 is detachably joined and fixed. The steel plate 24 prevents wear caused by the guide roller 10b relatively running on the side wall surface of the electrode lifting mast 7b ', and the aluminum alloy frame-like structure 23 is secondarily formed. Also plays the role of reinforcement.

The conventional electrode lifting mast is configured as a welded structure made of a steel plate. However, as has been clarified in the examination of the strength related to the electrode supporting beam, an aluminum alloy and a steel are used.
In the comparison of the strength per unit weight of (SS400), the aluminum alloy has 4.2 times the strength of steel, and the electrode lifting mast 7 according to this embodiment has the same structure.
b 'is compared with a conventional steel plate mast for raising and lowering the electrode.
The total weight can be about 24% while having the same strength. On the other hand, the electrode lifting mast 7b ′ according to this embodiment
8 (two on each side wall) are joined to the steel plate, but as mentioned above, the steel plate 24 is added for the purpose of preventing abrasion, and the thickness is extremely small. Therefore, the added weight is extremely small.

Further, since the steel plate 24 also plays a role of reinforcing the frame-like structure 23, the strength of the frame-like structure 23 is increased by the strength reinforcement.
Can be made thin to reduce the total weight of the electrode lifting mast 7b '. In particular, as shown in FIG. 4, if a steel plate 25, which is an L-shaped member, is joined to each corner of the frame-like structure 23, it is extremely effective for strength reinforcement,
The degree of weight reduction can be increased. The steel plates 24 and 25 need only be detachably joined to and fixed to the frame-shaped structure 23 by means of flathead screws or simple welding. What is necessary is just to remove it from the structure 23 and replace it, and it is not necessary to replace the entire lifting mast as in the conventional case.

Further, the electrode lifting mast 7 of this embodiment
Since the frame-like structure 23 of b ′ is made of an aluminum alloy that is a nonmagnetic material, electromagnetic induction heating is not caused by a large current flowing through the electrode support beam 3 ′. Therefore, the top plate 8b 'of the frame-like structure 23 does not need to be a water-cooled top plate 8b as shown in FIG. 6, and in that sense, the weight of the electrode lifting / lowering mast 7b' can be reduced. In addition, it is possible to reduce the cause of a water leakage accident.

[0023]

According to the present invention, the "electrode support beam and electrode lifting / lowering mast of the electric arc furnace" having the above-described structure has the following effects. The invention of claim 1 is
An electrode supporting beam having low electric resistance and light weight is realized, power loss is reduced, and a driving motor having a small capacity can be applied. In addition, due to the weight reduction, when a drive motor having the same capacity as that of the related art is used, the responsiveness of the electrode up / down control can be improved. According to the second aspect of the present invention, it is possible to realize an electrode raising / lowering mast whose weight is significantly reduced while maintaining sufficient strength, and it is possible to obtain the same effect as the first aspect of the present invention with respect to a drive system. In addition, the use of the aluminum alloy prevents electromagnetic induction heating due to the large current of the electrode support beam, and eliminates the need for a water-cooled top plate. Furthermore, by applying a steel plate to the contact surface with the guide roller, wear can be prevented, and even if worn, it can be easily replaced, eliminating the need to replace the entire mast. This also has the advantage that the weight can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a set of electrode lifting / lowering systems to which an electrode supporting beam and an electrode lifting / mast of an electric arc furnace according to the present invention are applied.

FIG. 2 is a cross-sectional view (corresponding to a cross-sectional view taken along line DD in FIG. 1) of an electrode support beam.

FIG. 3 is a cross-sectional view (corresponding to a cross-sectional view taken along arrow EE in FIG. 1) of an electrode lifting mast.

FIG. 4 is a cross-sectional view of an electrode lifting mast to which an L-shaped steel plate is attached.

FIG. 5 is a plan view showing an arrangement of electrode holders and electrode support beams in a three-phase AC arc furnace.

FIG. 6 is an overall configuration diagram of a set of electrode lifting / lowering systems to which a conventional electrode supporting beam and an electrode lifting / mast are applied (FIG. 5);
FIG.

7A is a cross-sectional view of an electrode supporting beam (corresponding to a cross-sectional view taken along the arrow BB in FIG. 6), and FIG. 7B is a cross-sectional view of an electrode lifting mast (FIG. 6).
(Corresponding to a cross-sectional view taken along the line CC in FIG. 1).

[Explanation of symbols]

1a ~ 1c ... graphite electrode, 2a ~ 2c ... electrode holder, 3a ~ 3c, 3b '
… Electrode support beam, 5b… flexible cable, 6b… insulating plate, 7b, 7b ′… electrode lifting mast, 8b, 8b ′… top plate, 9b… elevating sheave, 10b… guide roller, 11b… elevation control unit ( 12b… drum, 13b… wire rope, 14b, 15b
… Port, 16b… Partition plate, 21… Copper plate, 22… Aluminum alloy plate, 23… Frame structure (made of aluminum alloy), 24…
Steel plate, 25 ... steel plate (L-shaped member).

Claims (2)

[Claims] 1. An electrode support beam for an electric arc furnace, wherein the frame-like structure is constituted by a superposed plate of a copper plate and an aluminum alloy plate. 2. An electrode lifting mast for an electric arc furnace, wherein the frame-like structure is made of an aluminum alloy, and a steel plate is joined to a contact surface with a guide roller for guiding while supporting the electrode lifting mast. A mast for raising and lowering an electrode of an electric arc furnace, wherein