WO2013133318A1

WO2013133318A1 - Titanium melting device

Info

Publication number: WO2013133318A1
Application number: PCT/JP2013/056125
Authority: WO
Inventors: 瑛介黒澤; 中岡　威博; 一之堤; 大山　英人; 秀豪金橋; 石田　斉; 大喜高橋; 大介松若
Original assignee: 株式会社神戸製鋼所
Priority date: 2012-03-06
Filing date: 2013-03-06
Publication date: 2013-09-12
Also published as: JP5878398B2; JP2013184173A

Abstract

　The titanium melting device (1) according to the present invention is provided to a device for continuously manufacturing titanium ingots (55), and causes molten metal (53) obtained from a starting-material (51) (titanium sponge) to flow downward and pour into a mold (4). The titanium melting device (1) is provided with: a starting-material melting hearth (2), which melts an inputted starting-material (51) by means of plasma heating, forming a molten metal; and an electromagnetic stirrer (6), which is arranged close to the bottom surface of the starting-material melting hearth (2), and which stirs the molten metal (53) by generating a swirl flow in the molten metal (53) inside the starting-material melting hearth (2).

Description

Titanium melting equipment

The present invention relates to a titanium melting apparatus provided in an apparatus for continuously producing an ingot of titanium or a titanium alloy.

As an apparatus for continuously producing an ingot of titanium, for example, an apparatus described in Patent Document 1 has been proposed. The apparatus described in Patent Document 1 is configured to provide a solenoid coil at a position surrounding the plasma electron gun, the hearth, and the mold, and generate a magnetic field by the solenoid coil. Patent Document 1 describes that by generating a magnetic field parallel to the plasma electron beam flow, the plasma electron beam can be focused, the beam density can be adjusted, and the molten state of the molten metal can be controlled. . Patent Document 1 also describes that since the molten metal is magnetically stirred on the water-cooled copper hearth, complete melting and refining of the raw material can be performed by complete mixing.

Japanese Unexamined Patent Publication No. 48-51835

The present inventors are working on development of an apparatus for continuously producing an ingot of titanium (pure titanium) or a titanium alloy. Here, for example, there are two methods for dissolving the raw material solid titanium. One is a method in which a raw material lump is molded into a rod material or a block material in advance, and this rod material or the like is directly melted. The other is a method in which raw material lump (sponge titanium, remaining material, scrap, etc.) is put into a hearth (holding container), and these are melted with hearth. The method of directly dissolving the rod material or the like is costly for the molding of the raw material, and the dissolution rate is slow. Therefore, the method of charging the raw material into the hearth and dissolving it with hearth is more effective. The apparatus described in Patent Document 1 also employs a method in which the raw material charged into the hearth is dissolved by the hearth.

Here, since the dissolution rate of titanium is slow, when the raw material is melted with hearth, there is a risk that the unmelted raw material will flow into the latter mold. In addition, there is a possibility that an operation trouble such as a raw material that cannot be melted sinks to the bottom of the hearth or adheres to the inner wall of the hearth.

Such concerns also apply to the apparatus described in Patent Document 1. In the apparatus described in Patent Document 1, a solenoid coil is provided at a position surrounding all devices such as a plasma electron gun, a hearth, and a mold. This solenoid coil adjusts the beam density of the plasma electron beam. Moreover, the magnetic stirring of the molten metal on water-cooled copper hearth is performed by this solenoid coil. That is, the solenoid coil described in Patent Document 1 focuses on the adjustment of the plasma electron beam, and there is a concern that the molten metal may not be sufficiently stirred in the hearth. As a result, there is a possibility that an operation trouble such as the unmelted raw material flows into the mold, or the unmelted raw material settles on the bottom of the hearth or adheres to the inner wall of the hearth.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a titanium melting apparatus having a structure capable of sufficiently stirring the molten metal in the hearth as compared with the prior art.

The present invention is provided in an apparatus for continuously producing an ingot of titanium or titanium alloy, and melts solid titanium or titanium alloy, which is a raw material, by plasma heating to form a molten metal, and then flows the molten metal down into a mold. This is a titanium melting apparatus. This titanium melting apparatus is charged with raw material solid titanium or titanium alloy, and is disposed in proximity to the raw material melting hearth to be melted by melting the raw material by plasma heating, and the bottom surface of the raw material melting hearth, An electromagnetic stirrer that stirs the molten metal by generating a swirling flow in the molten metal in the raw material melting hearth.

According to the titanium melting apparatus of the present invention, the molten metal can be sufficiently stirred in the hearth than in the past. As a result, it is possible to further prevent operational troubles such as the undissolved raw material flowing into the mold, or the undissolved raw material sinking to the bottom of the hearth or adhering to the inner wall of the hearth.

(A) is a top view of the principal part of the casting apparatus which comprises the titanium melting apparatus which concerns on one Embodiment of this invention, (b) is AA sectional drawing of (a), (c) FIG. 4 is a cross-sectional view taken along line BB in FIG. It is a figure which shows the modification of the titanium melt | dissolution apparatus shown in FIG. It is a figure which shows the modification of the titanium melt | dissolution apparatus shown in FIG. It is a figure which shows the hearth for raw material melt | dissolution which concerns on a comparative example.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings.

(Configuration of titanium dissolution apparatus)
Fig.1 (a) is a top view of the principal part of a casting apparatus provided with the titanium melting | dissolving apparatus 1 which concerns on one Embodiment of this invention. 1B is a cross-sectional view taken along the line AA in FIG. 1A, and FIG. 1C is a cross-sectional view taken along the line BB in FIG.

The titanium melting apparatus of the present invention is provided in a casting apparatus that continuously manufactures an ingot of titanium or a titanium alloy. The titanium melting apparatus of the present invention works by melting solid titanium or a titanium alloy as a raw material by plasma heating to form a molten metal, and then pouring the molten metal into a mold.

As shown in FIG. 1, the titanium melting apparatus 1 of the present embodiment includes a raw material melting hearth 2 and an intermediate hearth 3. The molten metal 53 in which the raw material 51 is melted by the plasma gas from the plasma torch 5 flows down from the raw material melting hearth 2 to the intermediate hearth 3 and flows from the intermediate hearth 3 into the mold 4. In this embodiment, as an example, porous sponge titanium (pure titanium) is used as a raw material.

Note that the

hearths

2, 3 and the mold 4 are placed in a container called a chamber (not shown). Around the

hearths

2 and 3 and the mold 4 (inside the chamber) is an inert gas atmosphere filled with an inert gas such as argon gas or helium gas.

(Heart for melting raw materials)
The raw material melting hearth 2 is a holding container having a bottom, and plays a role of melting the raw material 51 (sponge titanium) by plasma heating to form a molten metal 53. The hearth 2 for melting the raw material is opened upward, and the inner peripheral wall and the outer peripheral wall are both square in plan view. As shown in FIG. 1A, when the length of one side of the inner peripheral wall of the raw material melting hearth 2 is L1, and the length of one side perpendicular thereto is L2, L1 = L2. Note that four corner portions (corner portions) of the inner peripheral wall of the raw material melting hearth 2 are chamfered in an arc shape. As described above, in the present invention, the square shape includes not only a square (a quadrangle in which all the inner angles are right angles and all the sides are equal), but also a square in which corner portions (corner portions) are chamfered.

The inner peripheral wall and / or outer peripheral wall of the raw material melting hearth 2 may be rectangular. When the inner peripheral wall of the raw material melting hearth 2 is rectangular, the ratio of the long side length to the short side length is preferably 1.5 or less. That is, in FIG. 1A, the value of L1 / L2 or L2 / L1 is preferably 1 or more and 1.5 or less. The square is a kind of rectangle.

Furthermore, the inner peripheral wall and / or outer peripheral wall of the hearth 2 for melting the raw material may be an ellipse or a circle. When the inner peripheral wall of the raw material melting hearth 2 is an ellipse, the ratio of the length of the major axis to the length of the minor axis is preferably 1.5 or less. That is, the value of “major axis length” / “minor axis length” is preferably 1 or more and 1.5 or less. A circle is a kind of ellipse.

Furthermore, the inner peripheral wall and / or outer peripheral wall of the hearth 2 for melting the raw material may be a polygon other than a rectangle. An example of the polygon is an octagon. When the inner peripheral wall of the hearth 2 for melting the raw material is, for example, an octagon, it is preferably a shape close to a regular octagon (a small aspect ratio).

The hearth 2 for melting the raw material is made of copper and is cooled with water. The same applies to the intermediate hearth and the mold.

A raw material charging path 9 is provided on one side wall of the raw material melting hearth 2. The raw material 51 is charged into the raw material melting hearth 2 from the raw material charging path 9. Further, a molten metal outlet channel 11 is provided in a side wall portion perpendicular to the one side wall provided with the raw material charging path 9. A molten metal 53 formed by melting the raw material 51 flows from the raw material melting hearth 2 into the intermediate hearth 3 via the molten metal outlet channel 11. The molten metal outlet channel 11 opens upward.

A plasma torch 5 (plasma heating device) is disposed above the raw material melting hearth 2. The plasma torch 5 is attached to the ceiling wall of the chamber via a bearing (not shown) so as to be slidable in the axial direction (movable up and down) and to be able to swing in any direction of 360 °. That is, the plasma torch 5 is attached to the chamber so as to penetrate the chamber. Further, the plasma torch 5 is electrically driven or hydraulically driven and is moved with a movement pattern set in advance according to a signal from a control device (not shown). The plasma torch 5 can also be moved manually by switching to manual. This also applies to the plasma torch 5 disposed above the intermediate hearth 3 described later, the plasma torch 7 disposed above the mold 4, and the plasma torches 5 and 7 shown in FIGS. . These plasma torches are also attached to the ceiling wall of the chamber so as to penetrate the chamber in such a manner that the plasma torch can slide in the axial direction (movable up and down) and can swing in any direction of 360 °. Further, these plasma torches are also electrically driven or hydraulically driven, or can be moved manually by switching to manual operation.

Here, a thick solid arrow in FIG. 1A moves (oscillates and / or slides) in the plasma injection part 5a (or the center of the plasma gas injected from the plasma injection part 5a) of the plasma torch 5. The range (movement pattern) to be moved (up and down movement) is illustrated. With this configuration, the plasma gas from the plasma torch 5 causes not only the molten metal surface of the molten metal 53 at the center of the raw material melting hearth 2 but also the raw material 51 (and the molten metal surface of the molten metal 53) of the raw material charging unit 2a, and the molten metal outlet. The molten metal surface of the molten metal 53 in the channel 11 can be plasma-heated with priority depending on the situation.

In FIG. 1A, if the plasma torch 5 disposed above the intermediate hearth 3 and on the left side of the center of the intermediate hearth 3 is disposed on the right side of the center of the intermediate hearth 3, for example, the plasma With the torch 5, the molten metal surface of the molten metal 53 in the molten metal outlet channel 11 can be plasma heated. That is, it is possible to simultaneously plasma-heat the molten metal surface of the raw material charging part 2a and the molten metal outlet channel 11.

(Electromagnetic stirring device)
An electromagnetic stirrer 6 is disposed under the raw material melting hearth 2. More specifically, the electromagnetic stirring device 6 is disposed close to the raw material melting hearth 2 at a predetermined interval with respect to the bottom surface of the raw material melting hearth 2. The electromagnetic stirring device 6 is a device for stirring the molten metal 53 by generating a horizontal swirling flow in the molten metal 53 in the raw material melting hearth 2. The electromagnetic stirring device 6 may be an EMS (Electro-Magnetic Stirrer) that energizes an alternating current, or may be a mechanical rotary type. Since the dissolution rate of titanium is slow, the flow rate in the raw material melting hearth 2 when only the dissolution of the titanium raw material is used without installing the electromagnetic stirring device 6 is about 1 cm / second at the maximum.

As shown in the stirring direction R of the molten metal 53 in FIG. 1A, the stirring direction of the molten metal 53 by the electromagnetic stirring device 6 is, among the two stirring directions from the raw material charging unit 2a to the molten metal outlet channel 11, It is preferable that the longer stirring direction is selected (the clockwise direction in FIG. 1A).

(Intermediate Hearth)
The intermediate hearth 3 is a holding container having a bottom, and plays a role such as equalizing the temperature of the molten metal 53, settling and separating the inclusions, and reducing changes in the amount of molten metal flowing into the mold 4 due to fluctuations in the molten amount. The intermediate hearth 3 is opened upward, and the inner peripheral wall and the outer peripheral wall thereof have a rectangular shape in plan view. Here, in the present embodiment, the raw material melting hearth 2 is disposed at one end of the long side of the four sides around the intermediate hearth 3, and the mold 4 is disposed at the other end of the long side. That is, the raw material melting hearth 2 and the intermediate hearth 3 are arranged in an L shape, and when the mold 4 is included, the whole is arranged in a U shape with a corner.

Here, at the end of the long side wall of the intermediate hearth 3, a molten metal injection channel 12 to the mold 4 is provided. The molten metal 53 that has flowed into the intermediate hearth 3 from the raw material melting hearth 2 flows down into the intermediate hearth 3 and then flows into the mold 4 via the molten metal injection channel 12. The molten metal injection channel 12 opens upward. The surface of the molten metal 53 flowing down in the intermediate hearth 3 is heated by plasma by a plasma torch 5 disposed above the intermediate hearth 3. Thereby, solidification of the molten metal 53 is prevented. In addition, the range which moves the plasma injection part (or the center of the plasma gas injected from a plasma injection part) of the plasma torch 5 arrange | positioned above the intermediate hearth 3 is a thick solid line arrow in Fig.1 (a). It is illustrated by.

(template)
The mold 4 is a mold having no bottom portion for solidifying the molten (injected) molten metal 53 into an ingot 55. Since the mold 4 has a rectangular cross section, a slab-shaped (cuboid) ingot 55 is obtained. The drawing device 13 is disposed under the mold 4, and the ingot 55 in which the molten metal 53 is solidified is cast while being drawn downward by the drawing device 13. In addition, the code | symbol 54 in FIG.1 (c) has shown the solidification part. A plasma torch 7 is disposed above the mold 4. The surface of the molten metal 53 that has flowed into the mold 4 is plasma heated by the plasma torch 7.

Here, the range in which the plasma injection part (or the center of the plasma gas injected from the plasma injection part) of the plasma torch 7 is moved is illustrated by a thick solid arrow in FIG. Since the plasma torch 7 is movable in such a range, both the molten metal surface of the molten metal 53 of the mold 4 and the molten metal surface of the molten metal injection channel 12 can be heated by the plasma gas from the plasma torch 7. .

In addition, by extending the moving range of the plasma torch 5 disposed above the intermediate hearth 3 to the molten metal injection channel 12, the molten metal 53 of the molten metal 53 in the molten metal injection channel 12 is caused by the plasma gas from the plasma torch 5. Heating is also possible.

(Action / Effect)
In the present invention, the electromagnetic stirrer 6 is disposed close to the bottom surface of the raw material melting hearth 2, and the electromagnetic stirrer 6 generates a swirling flow in the molten metal 53 in the raw material melting hearth 2 to stir the molten metal 53. Yes. According to this configuration, most of the electromagnetic stirring energy of the electromagnetic stirring device 6 can be used for stirring the molten metal 53 in the raw material melting hearth 2, and the molten metal 53 is sufficiently stirred in the raw material melting hearth 2. Can do. Thereby, dissolution efficiency improves. That is, the contact heat transfer rate from the molten metal 53 to the raw material 51 can be increased by increasing the contact speed between the raw material 51 and the molten metal 53. As a result, it is possible to further prevent operational troubles such as the undissolved raw material 51 flowing into the mold 4 or the undissolved raw material 51 sinking to the bottom of the hearth or adhering to the inner wall of the hearth. . In this embodiment, casting is performed while flowing the molten metal 53 continuously from Haas to Haas and from Haas to the mold. In such a case, an electromagnetic stirrer 6 is disposed close to the bottom surface of the raw material melting hearth 2 located at the most upstream, and a swirling flow is generated in the molten metal 53 in the raw material melting hearth 2 to stir the molten metal 53. It is especially important to do. Further, since the melting efficiency of the raw material 51 is improved, it is possible to reduce the size of the raw material melting hearth 2 and there is an advantage that the power efficiency is improved.

In the present embodiment, the inner peripheral wall of the raw material melting hearth 2 has a square shape (L1 = L2). That is, in this embodiment, the inner peripheral wall of the raw material melting hearth 2 has a rectangular shape (or ellipse), and the length of the long side (or long axis) / short side (or short axis) of the inner peripheral wall. 1 or more and 1.5 or less. Thereby, disturbance of the swirling flow in the raw material melting hearth 2 can be prevented, and the swirling flow velocity can be kept high. As a result, the contact speed between the raw material 51 and the molten metal 53 is further increased. FIG. 4 is a view showing a raw material melting hearth 62 according to a comparative example. As shown in FIG. 4, in the raw material melting hearth 62 having a large aspect ratio, a weak flow region S is generated in the molten metal 53 in the hearth (the swirl flow is disturbed). As a result of the raw material 51 being blown to the region S where the flow is weak, the melting efficiency of the raw material 51 is lowered.

Furthermore, in this embodiment, the stirring direction of the molten metal 53 by the electromagnetic stirring device 6 is set to the stirring direction R having the longer distance among the two stirring directions from the raw material charging unit 2a to the molten metal outlet channel 11. Thereby, it can prevent that a short circuit flow generate | occur | produces between the raw material injection | throwing-in part 2a and the molten metal exit flow path 11, and can prevent effectively that the unmelted raw material 51 comes out from the hearth 2 for raw material melt | dissolution. it can.

Also, the molten metal 53 can be stirred in the intermediate hearth 3 by arranging the intermediate hearth 3 and flowing the molten metal 53 in the intermediate hearth 3. Note that an electromagnetic stirring device 6 may be disposed under the intermediate hearth 3. In this case, the strength of electromagnetic stirring is determined in consideration of the sedimentation efficiency of inclusions.

Further, the molten metal outlet channel 11 and the molten metal injection channel 12 are portions where the molten metal 53 is easily solidified. By making the surface of the molten metal 53 in the molten metal outlet channel 112 and the molten metal surface of the molten metal injection channel 12 plasma heated, it is possible to effectively prevent the molten metal 53 from solidifying in the flow channel portions. Can do.

(Modification 1)
FIG. 2 is a view showing a modification of the titanium dissolving apparatus 1 shown in FIG. In this modification, a rod-shaped titanium alloy is used as the raw material 52 as an example. In addition, the same code | symbol is attached | subjected about the structural member similar to the structural member shown in FIG.

When titanium alloy is used as a raw material, the residence time of the molten metal 53 in the hearth needs to be longer than when titanium (pure titanium) is used as a raw material. The ingot (product) of the titanium alloy needs to have a lower inclusion content than the ingot (product) of titanium (pure titanium). Therefore, when using a titanium alloy as a raw material, it is necessary to more reliably remove inclusions from the molten metal 53 by sedimentation separation.

In the titanium melting apparatus 102 of this modification, the square heart-shaped two

hearths

81 and 82 are used, so that the capacity of the hearth is increased and the residence time of the molten metal 53 is lengthened. A flow path 14 is provided between the intermediate hearth 81 and the intermediate hearth 82. Even if one large intermediate hearth is used, the residence time of the molten metal 53 can be lengthened, but by using a plurality of

intermediate hearts

81 and 82, a short-circuit flow from the raw material melting hearth 2 to the mold 4 (direct flow) Can be further prevented. Thereby, it is possible to prevent the unmelted raw material 52 from flowing into the mold 10.

Since the components of the titanium alloy raw material 52 are not uniform, it is necessary to sufficiently stir the molten metal 53 in the hearth. Also from this viewpoint, it is preferable to stir the molten metal 53 by causing the molten metal 53 in the raw material melting hearth 2 to generate a swirling flow by placing the electromagnetic stirring device 6 close to the bottom surface of the raw material melting hearth 2.

In addition, the thick solid arrow in FIG. 2 moves in the plasma injection part (or the center of the plasma gas injected from the plasma injection part) of the plasma torch 5 (or 7) (as in FIG. 1A) ( An example of a range of rocking and / or sliding movement (up and down movement) is illustrated. Also in this embodiment, the molten metal surface of the molten metal 53 of each

flow path

11, 12, 14 can be heated by plasma. This also applies to the titanium dissolving apparatus 103 shown in FIG. 3 described later.

Since the ingot of titanium alloy is mainly a cylindrical product, the mold 10 is a bottomless mold having a circular cross section.

(Modification 2)
FIG. 3 is a view showing a modification of the titanium dissolving apparatus 1 shown in FIG. In addition, the same code | symbol is attached | subjected about the structural member similar to the structural member shown in FIG.

The difference between the titanium melting apparatus 1 shown in FIG. 1 and the titanium melting apparatus 103 of this modification is the shape of the intermediate hearth and the arrangement of the hearth mold.

In the present modification, the inner peripheral wall and the outer peripheral wall of the intermediate hearth 8 are formed in a square shape in the same manner as the raw material melting hearth 2. Note that the capacity in the intermediate hearth 8 and the capacity in the intermediate hearth 3 shown in FIG. 1 are substantially the same.

Regarding the arrangement of the hearth and the mold, the raw material charging path 9, the raw material melting hearth 2, the intermediate hearth 8, and the mold 4 are arranged in a line in this order. Further, the molten metal 53 is injected into the mold 4 from the center of the long side wall of the mold 4. In the titanium melting apparatus 1 shown in FIG. 1, the molten metal 53 is poured into the mold 4 from the central portion of the side wall on the short side of the mold 4.

Here, the raw material charging path 9, the molten metal outlet flow path 11, and the molten metal injection flow path 12 are shifted from each other so that adjacent ones are not arranged in a straight line. This prevents the occurrence of a short-circuit flow (direct flow) from the raw material melting hearth 2 (and the raw material charging portion 2a) to the mold 4.

In each of the

titanium dissolving apparatuses

1 and 102 shown in FIGS. 1 and 2, the hearth is arranged in an L shape, and when a mold is included, the hearth is arranged in a U shape with a corner as a whole. In the

titanium melting apparatuses

1 and 102 shown in FIGS. 1 and 2, by arranging the hearth and the mold in this way, it is possible to prevent the occurrence of a short circuit flow (direct flow) from the raw material melting hearth 2 to the mold 4. ing.

Although the embodiments and modifications of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. Is.

This application is based on a Japanese patent application filed on March 6, 2012 (Japanese Patent Application No. 2012-049418), the contents of which are incorporated herein by reference.

1: Titanium melting device 2: Raw material melting hearth 3: Intermediate hearth 4: Mold 6: Electromagnetic stirrer 11: Melt outlet channel 12: Molten injection channel 51: Raw material (sponge titanium)
52: Raw material (rod shape)
53: Molten metal

Claims

Titanium melting apparatus provided in an apparatus for continuously producing an ingot of titanium or titanium alloy, melting solid titanium or titanium alloy as a raw material by plasma heating to form a molten metal, and pouring the molten metal into a mold Because
Raw material melting hearth is charged with solid titanium or a titanium alloy as a raw material, and the raw material is melted by plasma heating to form a molten metal,
A titanium melting apparatus, comprising: an electromagnetic stirring device that is disposed close to a bottom surface of the raw material melting hearth and causes a swirl flow in the molten metal in the raw material melting hearth to stir the molten metal.
The titanium dissolving apparatus according to claim 1, wherein
The inner peripheral wall of the raw material melting hearth is rectangular or oval,
Titanium melting apparatus, wherein (length of long side or long axis of inner peripheral wall) / (length of short side or short axis of inner peripheral wall) is 1 or more and 1.5 or less.
The titanium dissolving apparatus according to claim 1 or 2,
The raw material melting hearth has a raw material charging part and a molten metal outlet channel,
Titanium melting characterized in that the stirring direction of the molten metal by the electromagnetic stirring device is the longer stirring direction of the two stirring directions from the raw material charging section to the molten metal outlet channel apparatus.
The titanium dissolving apparatus according to claim 1, wherein
The raw material melting hearth has a raw material charging part and a molten metal outlet channel,
The titanium melting apparatus, wherein not only the molten metal surface in the raw material melting hearth but also the molten metal surface in the molten metal outlet channel can be heated by plasma.
The titanium dissolving apparatus according to claim 1, wherein
An intermediate hearth into which the molten metal flows from the raw material melting hearth,
The titanium melting apparatus, wherein the molten metal that has flowed into the intermediate hearth flows down into the mold after flowing down.
The titanium dissolving apparatus according to claim 5,
The intermediate hearth has a melt injection channel to the mold,
The titanium melting apparatus, wherein both the molten metal surface in the intermediate hearth and the molten metal surface in the molten metal pouring channel can be heated by plasma.