JPH0442048Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention supplies current to the molten metal injection nozzle itself, which is made of conductive carbon-containing refractory material, and utilizes heat generated by resistance heat to inject the nozzle into the refractory material. The present invention relates to an energization heating device that stably heats.

[Conventional technology]

For example, when producing slabs from molten steel using the continuous casting method, in order to avoid contact between the molten steel flow and the atmosphere due to product quality requirements, long nozzles, Refractory flow pipes such as immersion nozzles are installed, and molten steel is poured in an aerated state. These nozzles are subjected to thermal shock when hot molten steel passes through the tube at the start of casting. Further, the inner wall of the nozzle is exposed to wear and erosion caused by molten steel, reactions caused by molten steel components and powder components, and the like. Therefore, it is necessary to make the nozzle with a material that has excellent thermal shock resistance, abrasion resistance, erosion resistance, corrosion resistance, etc. To meet this demand, alumina-carbon refractories, which take advantage of the chemical stability of neutral materials such as alumina and carbon and the low expansion properties of carbon (graphite), have come to be used. It's coming.

On the other hand, in continuous casting, the temperature of molten steel during casting decreases at the beginning and end of casting, and at that time, a large amount of base metal tends to adhere to the inner wall of the nozzle. As a result, the flow state of the molten steel flowing through the nozzle is disturbed or stagnates, making it difficult to perform casting operations under stable conditions.

In order to prevent such metal adhesion, the nozzle made of alumina-carbon refractory material is electrically conductive. It was discovered in 1983 that direct heating was achieved by passing current through resistance heat.
- It is shown in the publication No. 64857. However, when using this electrical heating, there is poor contact between the nozzle outer wall and the electrode, and abnormal heating occurs at the contact portion.
Therefore, various improvement proposals have been made to improve this poor contact. For example, there is a method in which a contractible conductive material is interposed between the nozzle outer wall and the electrode (Japanese Unexamined Patent Publication No. 8517/1983).

[Problem that the invention attempts to solve]

However, in conventional electrical heating of nozzles,
Since the nozzle is supported only in one place at the top, when an electric or pneumatic drive device is used to bring the electrode into contact with the nozzle, the nozzle is likely to break due to impact loads or uneven loads. . Furthermore, the setting accuracy between the nozzle and the electrode is poor, making it difficult to achieve uniform contact during abutment, resulting in damage to the electrode and localized abnormal heat generation. As a result, it has become difficult to perform stable and effective electrical heating of the nozzle.

Therefore, the present invention has developed a mechanism that maintains good contact between the nozzle outer circumferential surface and the energized heating electrode, and also uses a simple mechanism to bring the energized heating electrode into contact with the nozzle outer circumferential surface with a uniform pressing force. An object of the present invention is to provide an energization heating device equipped with the following.

[Means for solving problems]

In order to achieve the purpose of the current heating device of the present invention, a pair of current heating electrodes are provided with a molten metal injection nozzle in between, one of the current heating electrodes is attached to a connecting rod via a universal joint, and the other is attached to a connecting rod via a universal joint. The present invention is characterized in that an energized heating electrode is attached to the connecting rod via a universal joint and a drive device, and that the connecting rod is provided with moving wheels that roll on a moving base.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 is a cross-sectional plan view showing an electric heating device in an embodiment in which the present invention is applied to an immersion nozzle disposed between a tundish and a mold;
The figure is a front cross-sectional view.

so as to come into contact with the outer peripheral surface of this immersion nozzle 1,
A pair of graphite electrodes 2a and 2b are provided as current-carrying heating electrodes. The graphite electrodes 2a and 2b are connected to a connecting rod 5 via a copper electrode 3 and a universal joint 4, respectively. Of these graphite electrodes,
The graphite electrode 2a on the left side of FIG. 1 is directly connected to the connecting rod 5 and serves as a fixed electrode. The other graphite electrode 2b is connected to the connecting rod 5 via the air cylinder 6, and can freely move forward and backward with respect to the immersion nozzle 1.

Further, the connecting rod 5 has a frame shape, and a moving wheel 7 is attached to the bottom of the frame. This moving wheel 7 rolls on a moving base 9 provided at the bottom of a cover 8 that extends from the bottom of a molten metal container such as a tundish.

When heating the refractory constituting the immersion nozzle 1, the graphite electrode 2b is moved forward in the direction of arrow A in FIG. 2 by the air cylinder 6 and brought into contact with the immersion nozzle 1. Furthermore, when the air cylinder 6 is activated,
The other graphite electrode 2a moves together with the connecting rod 5 on the moving base 9 via the moving wheels 7 in the direction of arrow B in FIG.

At this time, since the universal joint 4 is provided on the outside of the copper electrode 3, the graphite electrodes 2a and 2b can be brought into uniform contact with the outer peripheral surface of the immersion nozzle 1. Furthermore, even if there is a slight misalignment between the two or between the axis of the air cylinder 6 and the graphite electrode 2b, the misalignment is absorbed by the universal joint 4 and the outer peripheral surface of the immersion nozzle 1 and the graphite electrode 2a, 2b is maintained well. In addition, in order to improve the contact condition and lower the contact resistance, a compressible conductive material, such as a graphite sheet 10, is attached to the graphite electrode 2.
It is preferable to paste it on the tip side of a and 2b.

FIG. 3 shows the electrical heating device 11 in this way.
is shown set in the immersion nozzle 1 disposed between the tundish 12 and the mold 13.
In this state, the copper electrode 3 is connected to the power supply (not shown).
Then, electricity is applied to the immersion nozzle 1 via the graphite electrodes 2a and 2b. At the start of heating, a current of 1000 A was applied for 10 minutes, and then a current of 3000 A was supplied. When 30 minutes had passed since the start of energization, the outer peripheral surface of the immersion nozzle 1 reached the target temperature of 1500°C. While maintaining this state, move from tundish 12 to mold 1.
When molten steel was injected into No. 3, it was possible to continuously pour molten steel from a 240-ton ladle into five ladle portions. During the casting operation, the immersed nozzle 1 could be heated under stable conditions without abnormal heat generation occurring in the portion of the immersed nozzle 1 where the graphite electrodes 2a, 2b are in contact. Furthermore, no metal was observed to adhere to the inner wall of the immersion nozzle 1.

[Effect of idea]

As explained above, in the present invention, by making one side of the graphite electrode connected to the movable connecting rod through the universal joint movable back and forth, the graphite electrode can be applied to the outer circumferential surface of the nozzle with the same pressing force. An electrode can be brought into contact with it. Therefore, the equipment can be made more compact and the cost of the equipment can be reduced. Furthermore, since the mutual gap between the graphite electrodes is restrained by the connecting rod, the state of contact between the nozzle and the graphite electrodes will not deteriorate due to external impact. In this way, according to the present invention, it is possible to carry out electrical heating under stable conditions, the durability of the nozzle is improved, and the casting operation is also stabilized by preventing base metal adhesion.

[Brief explanation of the drawing]

Fig. 1 is a plan sectional view showing the energization heating device according to an embodiment of the present invention, Fig. 2 is a front sectional view thereof, and Fig. 3 is a immersion nozzle placed between the tundish and the mold. Shows the set state.

Claims (1)

[Scope of utility model registration request] A pair of current-carrying heating electrodes are provided with the molten metal injection nozzle in between, one of the current-carrying heating electrodes is attached to the connecting rod via a universal joint, and the other current-carrying heating electrode is attached to the connecting rod via the universal joint and a drive device. An electrical heating device for a molten metal injection nozzle, characterized in that a movable wheel that is attached and rolls on a movable base is provided on the connecting rod.