JPH036860B2 - - Google Patents

Description

Claim 1: In a portion surrounded by an outer mold 3 and an inner mold 4, which are arranged concentrically and are movable relative to each other, and a pan 5 arranged between the molds 3 and 4, In the method for manufacturing a hollow billet by electroslag remelting, the inner mold 4 and the pan 5 are heated to a temperature of 0.8 to 0.95 times the melting point of the electrode 1 before remelting. The first layer of the billet is heated to is formed by the material constituting the electrode 1, the second layer of the billet is formed by the material constituting the outer mold 3, and the remelting step ensures that the billet produced is at the height of the outer mold 3. 0.7 or more
A method for producing hollow billets by electroslag remelting, characterized in that the process is carried out until a height of 0.9 is reached.

2 When the billet reaches approximately half the height of the outer mold 3, the heating energy for producing the hollow billet reaches the initial value of the heating energy for producing the hollow billet. 2. A method for producing hollow billets by electroslag remelting according to claim 1, characterized in that the electroslag remelting is reduced by a factor of 0.5 to 0.8.

3. The entire height of the outer mold 3 is cooled after the height of the hollow billet reaches 0.7 to 0.9 times the height of the outer mold 3. A method for producing a hollow billet by electroslag remelting according to scope 1 or 2.

4 The part of the outer mold below the intermediate layer 6 is cooled, and the intermediate layer 6 is cooled by the slag and the electrode 1.
The electroslag according to claim 1 or 2, characterized in that the intermediate layer is provided at a position between 0.1 and 0.5 times the height of the slag bath 2. A method of producing hollow billets by remelting.

5 has an outer mold 3 and an inner mold 4 arranged concentrically, and the outer mold 3 and the inner mold 4
In an apparatus for producing a hollow billet by electroslag remelting, the consumable electrode 1 can be moved relative to each other when it is remelted. The maintenance members 14, 14, . . . maintain a constant distance between the outer mold 3 and the inner mold 4, and the maintenance members 14 An apparatus for producing a hollow billet by electroslag remelting, characterized in that it comes into contact with the inner surface of the outer mold 3.

6. The apparatus for manufacturing a hollow billet by electroslag remelting according to claim 5, wherein the maintenance member 14 is removable.

7 Between the above-mentioned maintenance member 14 and the above-mentioned inner mold 4
An apparatus for producing hollow billets by electroslag remelting according to claim 5 or 6, characterized in that the device is made of a material that melts at a temperature higher than the melting point of the material.

TECHNICAL FIELD The present invention relates to electrometallurgy, and more particularly to a method for producing a hollow billet by remelting electroslag, and a billet production apparatus for carrying out this method.

BACKGROUND OF THE INVENTION There is a well-known method for remelting electroslag to produce hollow billets; (See page 67 of Paton et al., Electroslag Remelting Furnace, Naukova Dumka, Kiev, 1976).

The known methods for manufacturing hollow billets described above are difficult to implement. The reason is,
The problem lies in the fact that the electrodes of the consumable type are manufactured by melting one by one, and that it is difficult to fit the electrodes into a circular chamber for manufacturing a hollow bitlet.

Moreover, the equipment for carrying out the known method for manufacturing hollow billets is extremely large. The reason for this is that the electrodes used are longer than necessary. However, a fatal drawback of the known method is that it is not possible to produce hollow bimetallic billets.

Other methods are also known for producing hollow bitlets by remelting electroslag using consumable electrodes. In this known method, an outer mold and an inner mold are arranged concentrically and a pan is provided between them, in which the electrode is remelted. The inner mold and the outer mold can be moved relative to each other, the outer mold being cooled and the cooling being controlled. In a modification of the known method, the formation of a hollow billet is started in the pan, the formed billet is lowered together with the inner mold, and the outer mold is continuously cooled. As a result, hollow billets can be manufactured continuously (UK Patent No. 1261832, classification number B3F,
(see BEPaton et al., 1972).

A disadvantage of the known method is that it is not possible to produce bimetallic billets in hollow form.

Furthermore, devices are known for producing hollow bitlets by remelting electroslag using consumable electrodes. In this known device, an outer mold and an inner mold are arranged concentrically, and a hollow billet-forming section is formed between the molds.

The inner mold and the outer mold move relative to each other. For example, when gradually forming a hollow billet in the billet forming part using a consumable electrode,
Lower the outer mold. (BEPaton)
et al.; Electroslag remelting furnace; Naukova Dumka, Kiev; 1976;
(See pages 281-282 and Figure 302).

Hollow billets produced with this known device have a generally large variation in edge thickness. This is because the central axis of the inner mold, which should be vertical, is separated from the vertical axis of the outer mold. Therefore, when machining the manufactured billet, it is necessary to take a large cutting or cutting allowance. This is not desirable, especially in the case of bi-metal billets.
This results in the inconvenience of increased usage of non-ferrous metals and other expensive metals.

DISCLOSURE OF THE INVENTION The basic object of the present invention is to provide a method for remelting electroslag to produce hollow billets;
The object of the present invention is to provide an apparatus for manufacturing high quality hollow billets made of two types of metals using this method.

The above purpose is to recycle the consumable electrodes in a part surrounded by an outer mold, an inner mold, which are arranged concentrically and are movable relative to each other, and a pan arranged between both molds. In a method for producing hollow billets by electroslag remelting, the inner mold and pan are heated to a temperature of 0.8 to 0.95 times the melting point of the electrode before remelting, and then 2. The electrode is remelted without heating the outer mold and the inner mold to produce a hollow billet of different metals, and a first layer of the billet is formed of the material constituting the electrode. , the second layer of the billet is formed by the material constituting the outer mold, and the remelting step is carried out until the billet produced reaches a height of 0.7 to 0.9 of the height of the outer mold. This is achieved by a method of manufacturing hollow billets by electroslag remelting characterized by:

To prevent the outer mold from burning out (when the billet reaches approximately half the height of the outer mold), the heating energy for producing the hollow billet is transferred to the hollow billet. The initial value of heating energy to produce a billet of
Preferably, it is reduced by 0.5 to 0.8 times.

In order to prevent the mold from burning out, a hollow billet made of two types of metal is used to prevent the mold from burning out.
It is also possible to cool the outer mold over its entire height when the double height is reached.

In addition, from the viewpoint of improving the quality of the billet, an intermediate layer is provided between the slag and the metal of the electrode, and the position of the intermediate layer is 0.1 to 0.5 times the height of the slag bath. It is practical to cool the portion of the outer mold below the intermediate layer.

The above object also has an outer mold and an inner mold arranged concentrically, the outer mold and the inner mold being able to move relative to each other when the consumable electrode is remelted. In an apparatus for manufacturing a hollow billet by remelting, three or more retaining members are provided along the periphery of the inner mold, and the retaining members are provided between the outer mold and the inner mold. This is achieved by an apparatus for producing hollow billets by electroslag remelting, in which the gap is kept constant and the retaining member is in contact with the inner surface of the outer mold.

Between the above: The maintenance member has a removable structure,
Preferably, it is made of a material that melts at a higher temperature than the melting point of the inner mold material.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional view of a hollow billet manufacturing apparatus according to the present invention, Fig. 2 is a longitudinal cross-sectional view of an apparatus in which outer mold cooling is added to the hollow billet manufacturing apparatus of Fig. 1, and Fig. 3 is a longitudinal cross-sectional view of a hollow billet manufacturing apparatus according to the present invention. Figure 4 is a plan view of the apparatus shown in Figure 3, and Figure 5 is an improved version of the apparatus shown in Figure 1. It is an enlarged view of apparatus A.

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the present invention will be exemplarily described below with reference to the drawings.

The method of producing hollow billets of two metals by electroslag remelting in accordance with the present invention is carried out as follows.

The consumable electrode 1 (FIG. 1) is melted in a slag bath 2. This slag bath 2 includes molds 3 and 4,
It is made in a slag bath formed by a bottom saucer or pan 5. One layer of the bimetallic hollow billet produced in this slag bath is made of the material of the consumable electrode, and the other layer of the electrode is made of the material of the outer mold 3.

When performing the melting, the molds 3 and 4 are not cooled. Inner mold 4 and pan 5 before starting remelting
heat up. The purpose of this heating is to melt the slag and create a slag bath before the electrode begins to re-melt. This heating takes place below the melting point of the electrode.
Continue until the temperature reaches 0.8 to 0.95 times.

The lower limit of the above temperature range is determined based on the average melting temperature of slags widely used for remelting electroslag metals. The upper limit of the temperature range is determined based on the condition that the electrode 1 inserted into the molten slag does not melt before the remelting starts.

The above temperature range is shown as an example in the present invention, but in the case of manufacturing a "steel-copper" hollow billet, it is set at 860° to 1020°C. In this case, the mold 3 is made of steel, the mold 4 is made of graphite, the electrodes are made of copper, and the slag is made of a material based on creolite and fluospar.

During electroslag remelting, molds 3 and 4
Do not cool. With the electrode inserted into the slag bath 2, electricity is supplied to the electrode via the slag bath, and this electricity causes heat to melt the electrode and temperature of the uncooled wall of the mold 3. Generates heat to raise the temperature. This process involves using two types of metal, namely the metal of the mold 3 and the electrode 1.
This is a measure to prevent the metals from separating.

During the remelting, the molds 3 and 4 are moved relative to each other. This movement can be done in any conventional manner. Remelting continues until the billet produced reaches a height of 0.7 to 0.9 times the height of the mold 3. The value of 0.7 times this mold is
This value was selected from the viewpoint of safety, that is, from the viewpoint of preventing the mold wall from burning out. On the other hand, the above-mentioned value of 0.9 was selected from the viewpoint of quality control to improve the adhesion of the metal layer of the manufactured billet.

The billet is 0.7 to 0.9 of the height of the outer mold 3.
As soon as the temperature reaches this point, the wall of the mold 3 starts to burn from the outside. In order to prevent this, the remelting operation is interrupted and the portion of the mold at the above height is sufficiently cooled.

It should be noted here that as long as the electroslag is remelted in the uncooled mold 3, there is always a risk of it burning out.
The reason is that the mold is heated to dangerous temperatures. The risk is particularly high at the final stage when the remelting state becomes almost constant. Therefore, in order to completely prevent the mold from burning out, the amount of current supplied should be reduced to 0.5 of the initial current.
Or lower it to about 0.8 times. In practice, it is most effective to reduce the current to the above level when the billet is approximately half the height of the mold.

The degree of current reduction mentioned above is a value selected taking into account the minimum operating conditions that must be observed in order to ensure reliable adhesion of the two layers of the billet. These minimum operating conditions include, for example, no slag skull and no penetration of molten copper into the steel. This concerns the lower limit of the range in which the current is reduced. The upper limit of the current reduction range is a value determined based on the upper limit of the range in which the mold does not burn out.

In order to improve the reliability of the operation, more precisely to completely prevent the vessel wall of the outer mold 3 from burning, the intermediate layer 6 of the outer mold 3 is
(Figure 2) Cool the lower part. This intermediate layer 6 is located between the slag layer and the metal of the electrode, and the height of this intermediate layer is equal to the height of the slag bath 2.
0.1 to 0.5 times, and the height of the upper surface of the cooling part is maintained constant.

The supply of coolant to the cooling part takes place, for example, by means of a manifold 7 having holes 8, 8, . . . and surrounding the outer surface of the outer mold 3.

The preferable height of the portion where the coolant contacts the wall of the outer mold 3 is selected so as to satisfy the following conditions. In other words, the lower limit (0.1) of this height value is the lower limit of the thermal conditions that can reliably form layers of two types of metals, that is, without burning the wall of the outer mold 3 and allowing the metal of the electrode to This is the lower limit value of thermal conditions that can initiate a transition from the metal layer of the electrode to the metal layer of the outer mold 3 without melting into the metal of the outer mold 3. On the other hand, the upper limit (0.5) of the above height value is the upper limit of the thermal conditions of the above process, that is, the inner surface of the outer mold 3 is partially melted and adheres to the electrode, and this This value corresponds to the thermal conditions for forming two types of metal layers under the same conditions. In this state, the wall of the outer mold 3 is ignited, but does not catch fire.

Below is an example of a test of a method for manufacturing a hollow billet made of two types of metals.

Test Example 1 Electroslag, an expendable electrode made of copper, was remelted under the following conditions. That is, a layer of slag consisting mostly of cryolite was formed in the working space. The working space was formed using an outer mold made of copper with an inner diameter of 300 mm and an inner mold made of graphite with an inner diameter of 200 mm. The inner mold was structured to be movable relative to the outer mold. The lower part of the working space was separated using bread. This pan was placed between both molds. The inner mold and pan were heated to approximately 850° C. before remelting began. After that,
A consumable copper electrode was melted. This melting of the electrode can be carried out without cooling the outer mold, with a height of 1
I went until I reached m. The height of the manufactured billet is 0.7 meters.

Test Example 2 It was conducted in almost the same manner as Test Example 1. The difference is that the inner and outer molds are heated to approximately 1000℃, and the height of the billet to be made is 0.8℃.
This means that it was made into meters.

Test Example 3 Test Example 2 was conducted in almost the same manner. The differences are that the height of the billet produced was 0.4 meters, and the power required for remelting was approximately 40 kilowatts.

Test Example 4 It was conducted in almost the same manner as Test Example 3. The difference is that after the billet was made to a height of 0.4 meters, the power required for remelting was approximately 60 kilowatts.

Test Example 5 It was conducted in almost the same manner as Test Example 1. The difference is that after the billet was made to reach a height of 0.7 meters, the outer mold was cooled from bottom to top.

Test Example 6 It was conducted in almost the same manner as Test Example 2. The difference is that after the billet was made to reach a height of 0.8 meters, the outer mold was cooled from bottom to top.

Test Example 7 It was conducted in almost the same manner as Test Example 1. The difference is that a cooling part is provided in the outer mold, and this cooling part is located 10 mm below the middle layer, and this middle layer is provided between the slag and the metal layer of the electrode, and the cooling part is located 10 mm below the middle layer. The height of the top surface of the layer was maintained constant.

Test Example 8 It was conducted in almost the same manner as Test Example 1. The difference is that a cooling part is provided in the outer mold, the position of this cooling part is 30 mm lower than the intermediate layer, and this intermediate layer is provided between the slag and the metal layer of the electrode. be.

1 to 5 show a billet manufacturing apparatus for carrying out the method of manufacturing a hollow billet by electroslag remelting as described above.

The billet manufacturing apparatus has an outer mold 3, an inner mold 4 (FIG. 1), and a pan 5, and the outer mold 3, inner mold 4, and pan 5 are combined to perform remelting. form part. The inner mold 4 and the pan 5 are spiral heating members 9 and 1.
has 0. The outer mold 3 has a cooling device, which has connecting pipes 11, 12 for feeding and discharging the coolant, which connecting pipes 11, 12 extend around the outside of the space 13. It is attached. The molds 3, 4 are movable relative to each other, for example mold 4 can be lowered in the direction indicated by arrow B with any conventional device.

In order to improve the quality of the hollow billet made of two types of metals, the billet manufacturing apparatus is provided with gap maintaining members 14, 14, . . . (FIGS. 3 and 4). During this time, the maintenance member 14 is used to maintain the distance between the molds 3 and 4 constant. During this time, the maintenance member 14 is composed of lugs, which are attached to the outer edge of the mold 4 at regular intervals and come into contact with the inner surface of the mold 3.

The retaining member is removable and in the form of a shackle and is mounted around the upper part 16 of the mold 4, as shown in FIG. The lower part 17 of the shackle 15 aligns with the hole 18 in the outer surface of the mold 4.

The shackle 15 is made of a material having a higher melting point than the material of the inner mold 4. Therefore, if the inner mold 4 is made of steel (melting point is 1450° C.), the retaining member 14 is made of graphite. The melting point of graphite is 1700
It is ℃. The above shackle is also made of a material with a high melting point.
For example, it can be made using titanium, zirconium, etc.

FIG. 2 shows a billet manufacturing apparatus having a cooling device. This cooling device is in the form of a manifold 7, which has holes 8, 8,...
This hole 8 is attached to the outer mold 3.

The billet manufacturing apparatus shown in FIGS. 3 to 5 operates as follows.

The consumable electrode 1 melts into liquid metal, which accumulates in the mold 4, and this accumulated liquid metal is always held in the slag bath 2. Therefore, its temperature is extremely high. The liquid metal flows from the mold 4 into the space between the molds 3 and 4, where it comes into contact with the inner surface of the outer mold, and the outer mold 3 is heated by the slag bath. Ru. During this time, the outer mold 3 moves in an upward direction relative to the inner mold 4, and the inner mold 4 acts as a crystallizer.

The liquid metal of the electrode 1 is transferred to the mold 3.
crystallizes on the high-temperature vessel wall to form two metal layers that are fixed to each other, and these two metal layers
It becomes a hollow billet made of various metals.

The molds 3 and 4 are arranged between the maintenance members 14 and 1.
4,... allows relative movement. During this time, the maintenance member 14 is
When the molds 4 move relative to each other, the molds 3 and 4 act to align the vertical central axes of the molds 3 and 4 from beginning to end during the relative movement. Therefore, the thickness of the manufactured billet can be made uniform over the entire circumference. Therefore, it is possible to reduce the portion of the billet that is to be cut or scraped for machining. Therefore, the expensive and rare materials necessary for manufacturing the billet can be saved.

Between the above maintenance members 14, 14, . . .
Evenly spaced.

The number of the gap maintaining members is three or more, and when this number is three, the gap maintaining members are arranged 120° apart from each other (FIG. 4). The number of the gap maintenance members can be increased within a range that does not impair the purpose of use of the gap maintenance members.

During the above-mentioned shape, the maintenance member 14 is connected to the mold 3,
4 is kept constant throughout the movement of the molds 3 and 4. This is to keep the conditions for crystallizing the billet constant.

The method of manufacturing a hollow billet by remelting electroslag and the apparatus for carrying out the method described above have the following advantages. The advantages are that it is easy to implement, the manufacturing process is efficient, and the operation is reliable.

Industrial Applicability The present invention can be applied to the production of various devices and members including molds for electroslag remelting equipment.