JP5697105B2 - Electroslag remelting temperature measuring device and electroslag remelting temperature measuring method - Google Patents

Description

  The present invention relates to an electroslag remelting temperature measuring apparatus and an electroslag remelting temperature measuring method for measuring the temperature of a melting portion in electroslag remelting, for example, the temperature of molten slag or molten metal during melting.

  The electroslag remelting method is a process in which a large current is passed through a consumable electrode, the slag is melted by Joule heat generated at this time, and the consumable electrode is continuously melted in the molten slag. In this process, the temperature of the molten slag and molten metal in the electroslag remelting furnace affects the chemical composition of the resulting ingot, the composition and amount of non-metallic inclusions, and the solidification structure of the ingot. Temperature control of slag pools and molten metal pools is important in ingot quality control. Therefore, if these molten pool temperatures can be continuously monitored, it will help to improve quality.

  In Patent Document 1, a nozzle is disposed so as to penetrate the furnace wall of a container for holding a melt and have a tip in contact with the melt, and a guide pipe is built in by providing a gap in the nozzle. There has been proposed an apparatus for measuring the temperature of the melt by using a radiation thermometer that has passed through a metal tube-coated optical fiber coated with a metal tube and received radiation guided through the optical fiber. However, with this measuring device, the temperature can only be measured at a certain position on the furnace wall, and the melting part increases as the melting progresses, such as the electroslag remelting method. Thus, it is impossible to measure the temperature rise of the surface of the dissolution zone.

  On the other hand, in Patent Document 2, a metal tube is coated on an optical fiber, and the metal tube is sent downward together with the tip of the optical fiber by a fiber conveying means disposed above the furnace, inserted into the molten metal, and guided through the optical fiber. There has been proposed an apparatus for measuring the temperature of a molten metal using a radiation temperature measuring device that receives the emitted light. In this measuring apparatus, it is possible to cope with the position fluctuation of the melting portion by the amount of optical fiber delivered.

JP-A-9-159534 JP-A-5-248960

By the way, in the electroslag remelting method, as shown in FIG. 3, the path of the melting current flowing from the electroslag remelting electrode 1 by the voltage application to the electroslag remelting electrode 1 and the mold 2 by the power source 3 is the molten slag. It can be divided into a current passing path A1 flowing through the pool 4 → the molten metal pool 5 → the ingot 6 and a current passing path A2 flowing through the molten slag pool 4 → the mold 2. In general, an optical fiber generally used for measurement is coated with a metal such as stainless steel in order to protect a fiber made of SiO ₂ or the like. For this reason, the optical fiber is usually conductive. It is.

  In order to measure the temperature of the molten slag pool 4 or the molten metal pool 5 during melting of the electroslag, as shown in Patent Document 2, when the optical fiber is sent and immersed in these pools, the temperature inside the electroslag remelting furnace is the temperature. Distribution is not constant. For example, since the solid slag shell 7 is formed in the vicinity of the mold 2, the temperature variation of the molten slag around the mold 2 is large, and it is difficult to accurately measure the temperature in the vicinity of the solid slag shell 7. For this reason, in order to measure the temperature of a melt | dissolution part, it is necessary to consider a measurement position. In addition, in the electroslag remelting method, a magnetic field is generated around the electroslag remelting electrode 1 due to the melting current flowing in the electroslag remelting electrode 1, and the optical fiber line coated with metal is affected by the influence of this magnetic field. work. In a large electroslag remelting furnace, the depth of the mold is several meters to several tens of meters. If the optical fiber is not securely fixed at a predetermined position under the influence of such a magnetic field, there is a problem that it is difficult to measure an accurate temperature due to a shift in the measurement position.

  In addition, if the posture of the optical fiber is unstable, the conductive optical fiber may come into contact with the electroslag remelting electrode or the mold, and the optical fiber is grounded to the ground. Then, the dissolution current flowing in the electroslag remelting electrode may immediately flow to the ground side through the inserted optical fiber, and the electroslag remelting may stop (short circuit).

  The present invention has been made against the background of the above circumstances, and provides an electroslag remelting temperature measuring device and an electroslag remelting temperature measuring method capable of accurately and safely measuring the temperature of the melting part in electroslag remelting. The purpose is to provide.

That is, of the electroslag remelting temperature measuring apparatus of the present invention, the first present invention measures the temperature of the melting part in electroslag remelting to melt the electroslag remelting electrode while energizing to obtain an ingot. An electroslag remelting temperature measuring device that comprises:
An optical fiber that transmits the radiation emitted from the melting part, and a radiation thermometer that is connected to the optical fiber and receives the radiation transmitted by the optical fiber to detect the temperature of the melting part; A guide member fixed to the melting electrode and guiding the optical fiber so as to be continuous in the axial direction of the electroslag remelting electrode ;
The optical fiber or guide member is in electrical contact, and / or it can come into contact with during operation electrical device characterized that you have been electrically insulated with respect to the ground.

  The electroslag remelting temperature measuring apparatus according to the second aspect of the present invention is characterized in that, in the first aspect of the present invention, the guide member is made of metal or ceramic.

  The electroslag remelting temperature measuring device according to the third aspect of the present invention is characterized in that, in the first or second aspect of the present invention, the electroslag remelting temperature measuring device further comprises a delivery device for delivering the optical fiber guided by the guide member toward the melting portion. And

The electroslag remelting temperature measuring method according to the fourth aspect of the present invention is an electroslag remelting temperature for measuring the temperature of a melted part in an electroslag remelting method in which an electroslag remelting electrode is melted while energizing an electroslag remelting electrode. A measuring method,
A guide member is fixed to the electroslag remelting electrode, an optical fiber is positioned by the guide member so as to be continuous in an axial direction of the electroslag remelting electrode, and the optical fiber or the guide member is in electrical contact; And electrically insulate electrical equipment that may come into contact with the ground during operation, and continuously or temporarily send out the optical fiber toward the melting portion while guiding the optical fiber with the guide member. Accordingly, the radiated light of the melted part is transmitted by being incident on the optical fiber, and the temperature of the melted part is detected based on the radiated light transmitted by the optical fiber.

The electroslag remelting temperature measuring method of the fifth aspect of the present invention is characterized in that, in the fourth aspect of the present invention, the melting part is one or both of a molten slag pool and a molten metal pool.

Since the optical fiber line is usually low in rigidity, it is difficult to stably guide it to a predetermined measurement position only by sending out the optical fiber.
According to the present invention, the posture of the optical fiber is maintained by the guide member fixed to the electroslag remelting electrode, and the optical fiber can be accurately positioned at the measurement position. The guide member is preferably made of a metal or ceramic having high rigidity. It is desirable to use an oxide-based guide member made of ceramic. Further, since the ambient temperature in the vicinity of the electroslag remelting electrode is very high and there is a concern that the guide member is cracked or chipped due to thermal shock, it is more desirable to use a metal guide member. The guide member can be pipe-shaped, but any guide member can be used as long as it can guide the optical fiber so as to be continuous in the axial direction of the slag remelting electrode, and its shape is not particularly limited. .

Moreover, the guide member should just be a thing which can position an optical fiber so that it may continue in the axial direction of an electroslag remelting electrode, and arrangement | positioning of a guide member is arrange | positioned linearly along the said axial direction. It is not required. For example, the guide member may be spirally disposed around the electroslag remelting electrode.
The guide member moves downward by the lowering and melting of the electroslag remelting electrode, and is melted together with the electroslag remelting electrode and the optical fiber. In this case, since the amount of the guide member is small compared to the volume of the electroslag remelting electrode, the influence on the ingot can be ignored. For this reason, it is desirable to arrange the guide member so as to extend to the measurement start point of the electroslag remelting electrode, and it is also possible to arrange the guide member so as to be located at the tip of the electroslag remelting electrode from the beginning.
The guide member is normally fixed to the outer peripheral surface of the electroslag remelting electrode, but when the electroslag remelting electrode has a cylindrical shape or the like and has a hole along the axial direction, The guide member may be fixed in the hole.

  Further, the optical fiber can be sent out toward the melting part using a delivery device. The temperature of the melting member can be measured by sending out the optical fiber and inserting it into the melting part. The optical fiber may be sent out continuously or temporarily (for example, intermittently). When the optical fiber is inserted into the melting part, it melts in a short time due to the high temperature of the melting part, so the temperature from the predetermined depth of the melting part to the surface of the melting part can be adjusted by adjusting the feed length and feed speed as appropriate. It can be measured continuously.

  Generally, in the electroslag remelting method, the composition of the slag is selected so that the electrical resistance is increased in order to ensure the calorific value of the slag, and even if the optical fiber is not grounded, the resistance of the optical fiber to the ground Is small, part of the current flowing through the electroslag remelting electrode flows to the ground via the optical fiber. Such current flow fluctuates the amount of current flowing in the furnace, changes the temperature of molten slag and molten metal, changes the chemical composition of the ingot and the composition and amount of non-metallic inclusions, and casts. Since non-uniformity occurs in the solidified structure of the lump, it is not preferable in quality.

In order to surely avoid the current flow, it is desirable to electrically insulate an electrical device with which the optical fiber or the guide member may come into electrical contact or contact during operation.
Examples of the electric equipment include a radiation temperature measuring device and a delivery device, but the present invention is not limited to these. As a method of electrically insulating against the ground, for example, there is a method of supplying electric power to an electric device through an insulating transformer.

  As described above, according to the present invention, the temperature of the melted part in electroslag remelting can be measured accurately and stably, and the internal quality such as the chemical composition and solidification structure of the ingot can be improved. Become.

It is a figure which shows the block diagram of one Embodiment of this invention. Similarly it is a figure which shows transition of the temperature measured value of an Example, a dissolution current value, etc. FIG. It is a figure which shows the electric current passage route of the melt | dissolution current in the general electroslag remelting method.

Below, the electroslag remelting temperature measuring apparatus of one Embodiment of this invention is demonstrated using FIG.
The electroslag remelting furnace to be measured in this embodiment includes an electroslag remelting electrode 1, a mold 2, and a power source 3. In this embodiment, the power source 3 is an AC power source. However, the present invention is not limited to this and may be a DC power source.
The electroslag remelting electrode 1 is installed so as to be movable up and down along the central portion in the mold 2, and one end thereof is electrically connected to one of the output ends of the power source 3. The other output terminal of the power source 3 is connected to the mold 2, and a voltage can be applied between the electroslag remelting electrode 1 and the mold 2 by the power source 3.

The electroslag remelting temperature measuring device of the present embodiment has a guide tube 12 that is fixed to the outer peripheral surface of the electroslag remelting electrode 1 along the axial direction. The guide tube 12 has an inner diameter that allows the optical fiber 10 to be smoothly inserted through the optical fiber 10 and the posture of the optical fiber to be stably maintained. The guide tube 12 only needs to be able to guide the optical fiber 10 so as to be positioned continuously in the axial direction of the electroslag remelting electrode 1 and is linear along the axial direction of the electroslag remelting electrode 1. Although not required to be disposed, it is desirable that the guide tube 12 be disposed in a straight line and fixed to the electroslag remelting electrode 1 in order to smoothly send out the optical fiber 10. The guide tube 12 can be made of metal or ceramic. The guide tube 12 corresponds to the guide member of the present invention.
The tip of the guide tube 12 may be fixed to the outer peripheral surface of the electroslag remelting electrode 1 so as to reach the temperature measurement start position, and the guide tube 12 extends to the tip of the electroslag remelting electrode 1. It may be the one that reaches the tip. Furthermore, as long as the optical fiber 10 to be guided can be stably supported, the guide tube 12 may be arranged so that the optical fiber 10 protrudes. The guide tube 12 can be fixed by a fixture such as welding or rivet, and the fixing method is not particularly limited in the present invention.

Further, a delivery device 13 for sending the optical fiber 10 guided by the guide tube 12 downward is installed near the upper portion of the guide tube 12. The delivery device 13 can be controlled by a control unit including a CPU, a storage unit, and the like, and can set a delivery speed and a delivery amount. Further, power is supplied to the delivery device 13 from a power supply device 15 to be described later.
The optical fiber 10 is made of SiO ₂ or the like as a core wire, and is coated with a metal such as stainless steel in order to protect the core wire. One end of the optical fiber 10 is connected to the radiation temperature measuring instrument 11 and is inserted into the guide tube 10 via the delivery device 13. The optical fiber 10 may be inserted from the beginning so that the tip is located at a predetermined position in the guide tube 12, or may be sent to a predetermined position by the sending device 13.

As the radiation temperature measuring device 11, a known device can be used, and the temperature at the radiation light generation unit is measured by detecting the intensity of the radiation light. A recorder 14 is connected to the radiation temperature measuring device 11, and the measurement result can be recorded on a screen, paper, storage unit, or the like.
The radiation temperature measuring instrument 11 and the recorder 14 are connected to the output terminal of the power supply device 15, and the output terminal is connected to the secondary side of the insulating transformer 15a. A two-wire commercial power supply 16 is connected to the primary side of the insulating transformer 15a, and the one-wire side is grounded. Although not shown, the delivery device 13 is also connected to the output terminal of the power supply device 15 and is supplied with power from the power supply device 15.
The delivery device 13, the radiation temperature measuring device 11, and the recording device 14 correspond to electrical devices that the optical fiber 10 or the guide member 12 may come into electrical contact with and / or contact during operation.

Next, the operation of this embodiment will be described.
With the start of electroslag remelting, electricity is applied through the slag melted in the mold 2, and the electroslag remelting electrode 1 is immersed in the molten slag pool 4.
The electroslag remelting electrode 1 is melted by Joule heat of the molten slag pool 4, and the droplet reaches the bottom of the mold 2 while descending the molten slag pool 4 to form a molten metal pool 5. The molten slag pool 4 and the molten metal pool 5 correspond to a melting part.
The mold 2 is cooled by a cooling means (not shown), an ingot 6 is obtained below the molten metal pool 5, and a solid slag shell 7 is formed near the inner wall of the mold 2.
The electroslag remelting electrode 1 is moved downward in accordance with the degree of consumption and the liquid level of the molten slag pool 4 to maintain the inserted state in the molten slag pool 4, and the electroslag remelting electrode 1 is melted. Is performed continuously.

  When the electroslag remelting electrode 1 is dissolved and lowered, the guide tube 12 and the optical fiber 10 are lowered accordingly, and the guide tube 12 immersed in the molten slag pool 4 and the distal end side of the optical fiber 10 are dissolved. Disappear. At this time, by feeding a predetermined amount of the optical fiber 10, the tip can be positioned in the molten slag pool 4 or the molten metal pool 5. Radiant light radiated according to the temperature of the molten slag pool 4 or the molten metal pool 5 is incident on the optical fiber 10, and the radiated light is transmitted in the optical fiber 10 and reaches the radiation temperature measuring instrument 11. . The radiation temperature measuring device 11 can detect the temperature of the melted portion where the radiated light is radiated based on the intensity of the received radiated light and record it on the recorder 14.

The optical fiber 10 fed into the dissolving part is dissolved from the tip side, and the length in the dissolving part gradually decreases, and finally the tip of the optical fiber 10 is positioned on the liquid surface of the dissolving part. At this time, since the radiated light is incident on the optical fiber 10 from the position where the depth gradually decreases in the melting portion, the temperature at different depth positions in the melting portion can be measured.
At this time, by controlling the delivery device 13 by a control unit (not shown), the optical fiber 10 can be delivered continuously or intermittently according to a preset delivery speed, delivery amount, or the like. The temperature of the metal pool 5 can be continuously measured, and the measurement result can be fed back to the dissolution control.

In the above measurement, since the optical fiber 10 is stably supported and guided by the guide tube 12, the temperature of the melting portion can be accurately measured at the position guided by the guide tube 12, and the optical fiber 10 and the like. Does not contact the mold 2 or the like unexpectedly.
In addition, since the delivery device 13, the radiation temperature measuring device 11, and the recorder 14 to which the optical fiber 10 and the guide tube 12 are electrically connected are electrically insulated from the ground, the electroslag is re-transmitted through the optical fiber 10 and the like. Electroslag remelting can be operated in a stable state without causing current for melting to leak.

Below, the Example of this invention using the electroslag remelting temperature measuring apparatus of the said embodiment is described.
In this example, a commercially available radiation thermometer was used, and an optical fiber made of SiO ₂ and coated with SUS304 with an inner diameter of 2 mm was used. For the optical fiber delivery device, a wire feeder capable of controlling the delivery speed and amount constant was used. The feeding was performed intermittently, and the feed length was 15 mm / 1, the feed speed was 15 mm / second, and the interval was 15 seconds.
The electroslag remelting conditions at the time of measurement were as follows: Electroslag remelting electrode composition: 18Mn-18Cr-N-residual Fe, diameter: 40 mm, mold filling rate: 0.5, atmosphere: air, slag composition: CaF _2- Al ₂ O ₃ —CaO system, slag mass: 600 g, dissolution start method: hot start method, set current: 700 A, set voltage: 26 V.

  FIG. 2 shows the results of measurement using an electroslag remelting temperature measuring device during electroslag remelting under the above conditions. As shown in FIG. 2, the temperature of the melted part during operation could be measured stably. The measured temperature value increases as the optical fiber 10 is sent out, and then gradually decreases to a steady state. The upper limit of the measured value indicates the melting part temperature at the position of the lowest point of the sent optical fiber, and the steady state temperature indicates the temperature of the liquid surface of the dissolving part. In this embodiment, the temperature of the molten slag pool is measured, but it is also possible to measure the temperature of the molten metal pool depending on the delivery amount of the optical fiber.

  As described above, the present invention has been described based on the above-described embodiment and examples. However, the present invention is not limited to the above description, and appropriate modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Electroslag remelting electrode 2 Mold 3 Power supply 4 Molten slag pool 5 Molten metal pool 6 Ingot 7 Solid slag shell 10 Optical fiber 11 Radiation temperature measuring instrument 12 Guide tube 13 Feeder 14 Recorder 15 Power supply 15a Insulation transformer 16 Commercial power supply

Claims (5)

An electroslag remelting temperature measuring device for measuring the temperature of a melting part in electroslag remelting to obtain an ingot by melting while energizing an electroslag remelting electrode,
An optical fiber that transmits the radiation emitted from the melting part, and a radiation thermometer that is connected to the optical fiber and receives the radiation transmitted by the optical fiber to detect the temperature of the melting part; A guide member fixed to the melting electrode and guiding the optical fiber so as to be continuous in the axial direction of the electroslag remelting electrode ;
The optical fiber or guide member is in electrical contact, and / or electro-slag remelting temperature measuring device which is characterized that you have been electrically insulated electrical equipment that might come into contact with respect to the ground during operation.   2. The electroslag remelting temperature measuring apparatus according to claim 1, wherein the guide member is made of metal or ceramic.   The electroslag remelting temperature measuring device according to claim 1, further comprising a delivery device that sends out the optical fiber guided by the guide member toward the melting portion. An electroslag remelting temperature measuring method for measuring a temperature of a melting portion in an electroslag remelting method for obtaining an ingot by melting while energizing an electroslag remelting electrode,
A guide member is fixed to the electroslag remelting electrode, an optical fiber is positioned by the guide member so as to be continuous in an axial direction of the electroslag remelting electrode, and the optical fiber or the guide member is in electrical contact; And electrically insulate electrical equipment that may come into contact with the ground during operation, and continuously or temporarily send out the optical fiber toward the melting portion while guiding the optical fiber with the guide member. A method for measuring an electroslag remelting temperature, wherein the radiated light of the melting part corresponding to the incident light is transmitted by being incident on the optical fiber, and the temperature of the melting part is detected based on the radiated light transmitted by the optical fiber. The electroslag remelting temperature measuring method according to claim 4 , wherein the melting part is one or both of a molten slag pool and a molten metal pool.

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