JPH04162954A - Device for continuously melting and casting metal - Google Patents

Abstract

PURPOSE:To obtain a high purity and high quality ingot by arranging an upper range widening interval of sectors downward and a lower range dividing no sector in an electric conductive cooling type crucible divided into plural sectors in the height direction of a wall face. CONSTITUTION:After fixing base material for the ingot 6 to tip part of a pull- out bar 5, the pull-out bar is ascended and upper end of the base material is inserted to almost intermediate height of the crucible 2. Thereafter that, by supplying DC current of high frequency, etc., to an inductor 7, the base material is heated through gaps 2h of the crucible and melted. Successively, metal material 4 is continuously supplied on the base material. and also the pull-out bar is descended. As the metal material flowed into the gap and solidified, is acted to releasing direction to tensile stress developed at between the ingot and the crucible according to shifting of the ingot downward, crack on surface of the cast ingot is not developed. In the case of the crucible having grooves 2i, since the increase of the tensile strength at between the crucible and the ingot is avoided, the crack is not developed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a continuous metal melting and casting apparatus using a vertical cooling crucible in which induction heating is performed.

(Prior art) Cooling crucibles, which have been widely known for a long time, are used when melting highly reactive metal materials such as titanium silconium and producing ingots. equipment for melting and casting metals.

This cooled crucible is usually arranged in a chamber, and a conductive wall made of ordinary steel is surrounded by a copper cooled crucible made of sectors divided by slits, and the outer peripheral surface of the cooled crucible is surrounded by a conductive wall made of ordinary steel. It consists of an induction coil, a drawing device that supports the cast ingot, a feeder for slag agent, and a feeder for raw metal materials.

That is, as mentioned above, the outer wall of the cooling crucible is
It is divided into a plurality of longitudinal sectors, ranging from 4 to more than 20, which are circumferentially juxtaposed and electrically insulated from each other, and which are lined with a cooling fluid. is configured so that it circulates.

Furthermore, the cooled crucible is surrounded over a portion of its height by an induction coil, which is a cooled coaxial helical inductor. Since the outer wall surface of the cooling crucible is divided into sectors, an alternating magnetic field induces a current in the metal material due to the medium wave or high frequency alternating current applied to the induction coil.

As a result, the metal material is heated, melted, and stirred.

Various proposals have been made regarding metal melting apparatuses using such cooling crucibles.

For example, French Patent No. 2,497,050 discloses a device that gradually extracts the metal material in a solid state while drawing it downwards. Apparatus for continuous melting and casting has been proposed.

The device proposed by this French patent No. 2,497,050 is characterized by the fact that the metal material is subjected to electromagnetic pinching forces and there is a solidified slag film between the metal material and the wall over the entire height of said device. It has the characteristic that it does not come into direct contact with the crucible wall.

Furthermore, French Patent No. 2,609,655 discloses a continuous casting apparatus equipped with a cooling crucible, except that the cross-sectional area inside the cooling crucible at least expands downward and that no slag is used. Said French Patent No. 24
A device similar to the device proposed in No. 97050 has been proposed. The device proposed in French Patent No. 2,609,655 controls the amount of current supplied to the induction coil to control the liquid material to a small height at which the upper and lower regions of the cooling crucible are joined. Other than the part you have! It is possible to magnetically decouple it from the wall of the cooled crucible, where the liquid metal solidifies in contact with the side wall of the cooled crucible. Since the cross-sectional area inside the cooling crucible is changed between the upper region and the lower region, the solid metal comes into contact with the inner wall of the crucible at a limited height. Therefore, with this device, the ingot can be drawn relatively easily, the solidified metal is hardly contaminated by the metal in the crucible, and the tensile stress between the solid metal and the cooled crucible is limited to a small value. Therefore, the ingot can be expected to have a good surface condition.

(Problem to be solved by the invention a) However, each of these devices has its own problems, and the device proposed in French Patent No. 2,497,050 has the following problems: If there is contact over a long period of time, the resulting tensile stress will be large, and in the worst case, it may cause cracks on the cast surface of the ingot. ■The slag film that adheres to the ingot surface should be removed before processing the ingot. The slag has to be taken and removed, which increases the number of man-hours; slag can contaminate the molten metal material and corrode the cooling crucible; In the case of slag being carried out in the furnace, the slag is emitted from the warehouse and adheres to various parts inside the furnace, making it necessary to clean the inside of the furnace.In addition, the slag may deform the shape of the ingot into an arbitrary shape other than the inner shape of the crucible. There is a problem.

On the other hand, a problem with the device disclosed in French Patent No. 2,609,655 is that it is not easy to implement due to low productivity. In other words, when the ingot casting speed is increased to increase productivity, unsolidified material overflows into the space between the ingot and the cooling crucible, where the cross-sectional area of the inner wall surface expands downward, forming a double skin. In the worst case scenario, a breakout may occur.

Here, the purpose of the present invention is to solve the problems of the above-mentioned conventional technology,
In other words, (a) the problem of material contamination due to the presence of slag and the problem of additional steps due to stripping of the slag film; (a) the problem of cracks occurring on the casting surface of the ingot; The object of the present invention is to provide a continuous metal melting and casting device that can solve the problem of double skin and breakout occurrence.

(Means for Solving the Problems) The present inventor has conducted various studies in order to solve the above problems.

First, by repeatedly conducting basic experiments using conventional equipment, we found that: (a) In conventional equipment, slag is interposed between the ingot and the cooling crucible to prevent them from coming into contact with the inner wall surfaces of the crucible; However, even without using this slag,
Due to the presence of pinch force, etc., the casting is in a substantially electrically and thermally insulated state, and there is no practical problem, and in particular, the gap between adjacent sectors can be removed from other places in the crucible (e.g. It was theoretically predicted that the magnetic flux density would be higher than that in the sector installation part), and it was found that the possibility that molten metal material would flow into the gap part was even smaller.

However, the present inventor further examined in detail the results of an enormous amount of basic experiments. As a result, considering actual operation, disturbances such as changes in the liquid material scene due to the input of solid materials may occur, and when designing such equipment, it is important to It was found that it is necessary to take precautions against the possibility that liquid material may flow into the gap between the sectors.

As a result of various studies on measures to be taken in the event that liquid material flows into the gap between adjacent sectors, we found that (C) When liquid material flows into the gap between adjacent sectors, The liquid material solidifies within this gap and increases the tensile stress of the entire ingot. Therefore, in order to alleviate the tensile stress, the wall surface where the dimension of the sector gap increases along the casting direction (vertically downward). If a cooling type crucible with this structure is used, the stress between the ingot and the cooling type crucible during ingot drawing is alleviated, and the quality of the casting surface of the ingot is improved. an extension, by providing a groove in the lower part of said sector, which occurs between the solidified drift material and the cooled crucible, especially at or near the junction of the upper and lower regions where said gap disappears; (e) In crucibles having the structure shown in (C) or (d) above, it is desirable to improve the quality of the casting surface because the stress is alleviated. It has been found that since the cross-sectional area and the inner cross-sectional area of the lower region do not change, it is possible to prevent the occurrence of double skin or breakout during high-speed casting.

Based on such knowledge, the present inventors completed the present invention after further studies.

Here, the gist of the present invention is an apparatus for continuously melting and casting solid metal supplied from a square direction, in which a part of the wall surface in the height direction is divided into a plurality of sectors. an electrically conductive cooling crucible; a coil-shaped inductor disposed so as to partially surround the outer peripheral surface of the cooling crucible in the height direction; an apparatus for continuous melting and casting of metals, comprising: (i) a portion thereof divided into said sectors;
A metal continuum characterized by having an upper region having a structure in which the interval between each of the adjacent sectors increases as it goes downward, and (11) a lower region joined to the upper region and not divided into the sectors. It is a specialized melting and casting equipment.

Further, in the present invention, the lower region has a groove in the inner wall surface of the cooling crucible facing the ingot on an extension of the interval between the adjacent sectors, and the upper region where the gap disappears and the lower region This is more desirable from the viewpoint of improving the quality of the casting surface, since the stress generated between the solidified floating material and the cooling crucible at or near the joint with the region is alleviated.

Furthermore, in these inventions, the cooling crucible,
It is also preferred to have a chamber separating said coil-shaped inductor, feeder and withdrawal device from the atmosphere, preferably with a controlled atmosphere.

(effect) First, the present invention will be explained in detail along with its effects.

Briefly, the present invention is an apparatus for continuously melting and casting solid metal supplied from above, and the present invention is an apparatus for continuously melting and casting solid metal supplied from above. a cooling crucible; a coil-shaped inductor disposed so as to partially surround the cooling crucible in the height direction; and a device for pulling the ingot cast in the crucible downward. in a continuous metal melting and casting apparatus having: (i) a portion thereof divided into said sectors;
(ii) the upper region has a structure in which the distance between each of the adjacent sectors increases as it goes downward; and (ii) the upper region is provided following the upper region and is not divided into sectors and is an extension of the distance between the adjacent sectors. and a lower region with grooves in the crucible wall facing the ingot.

That is, in the present invention, a part of the structure is divided into the sectors and has an upper region in which the interval between the adjacent sectors increases as it goes downward, so that the liquid material does not flow into the gaps between the adjacent sectors. When this happens, in conventional continuous metal melting and casting equipment using cooled crucibles, the inflowing liquid material solidifies in the gaps between the sectors, increasing the tensile stress of the entire ingot when it is pulled. I'll let you.

However, according to the present invention, in order to alleviate the tensile stress, the structure of the cooling crucible is changed to a structure in which the size of the gap between adjacent sectors increases along the casting direction (vertically downward) (for example, each sector The structure in which the width of the ingot tapers off as it goes vertically downward reduces the stress between the ingot and the cooling crucible, improving the quality of the casting surface of the ingot.

Furthermore, if the extension part of the gap along the casting direction is made into a groove structure, the stress between the solidified drift material and the cooling crucible will be alleviated, especially at the junction between the upper and lower regions where the gap disappears. In order to improve the quality of the casting surface, the − layer is desirable.

Furthermore, in the cooling type crucible having the structure according to the present invention,
It is not necessary to change the cross-sectional area of the upper region involved in solidification and the inner cross-sectional area of the lower region, as in the device proposed by the aforementioned French Patent No. 2,609,655, which reduces the double skin during high-speed casting. or breakout can be prevented.

Note that in the cooling crucible used in the continuous metal melting and casting apparatus according to the present invention, as described above, the dimensions of the gap between the sectors that are in contact with each other are directed vertically downward in the casting direction).
The crucible may be similar to a conventional cooled crucible, except that it has a structure that expands along the crucible.

That is, the cooled crucible has an electrically conductive wall made of common steel, which wall has a plurality of longitudinal sectors, for example from 4 to 20 or more, which sectors are juxtaposed to each other. , and are electrically insulated from each other, and the interior of the sector is configured to circulate a cooling liquid.

Further, medium wave or high frequency alternating current is supplied to the spiral inductor. These structures may be the same as those of known sectors, and may be configured to satisfy such functions by appropriate means.

Next, a method for manufacturing an ingot by melting metal raw materials using the continuous metal melting and casting apparatus according to the present invention will be explained based on FIGS. 1 and 2.

FIG. 1 is a schematic explanatory diagram showing the structure of one embodiment of the continuous metal melting and casting apparatus according to the present invention, and FIG.
1 is a schematic perspective view showing the structure of a cooling crucible used in the continuous metal melting and casting apparatus according to the present invention.

First, after fixing the base material of the ingot 6 to the tip of the drawing rod 5, the drawing rod 5 is raised and inserted until the upper end of the base material corresponds to approximately the middle height of the cooling crucible 2.

Thereafter, when a medium-wave or high-frequency alternating current is supplied to the inductor 7, the induced current flows through the gap 2h in the upper region of the cooling crucible 2 to the inner surface of the crucible, so that the base material is heated and eventually melted.

Subsequently, the metal material 4 is continuously supplied onto the base material 3 which is in a molten state, and the drawing rod is continuously lowered at a speed corresponding to the material supply speed.

At this time, the liquid metal material 3 exists between adjacent sectors in the upper region of the crucible due to the impact when the solid metal material falls onto the molten metal material or disturbances such as induced stirring. It may flow into the gap and solidify there.

As mentioned above, the present invention is an apparatus for continuous melting and casting of metal using a cooled crucible whose structure is characterized in that the gap between adjacent sectors is configured to increase along the casting direction.

That is, the metal material that has flowed into the gap and solidified acts in a direction to relieve the tensile stress generated between the ingot and the cooling crucible as it moves downwards in the ingot 6, thereby causing cracks in the casting surface of the ingot surface. It will not occur.

Furthermore, as shown in FIG. 2, in the case of a cooled crucible having a structure having grooves 21 in the lower region of the cooled crucible, when the ingot moves from the upper region to the lower region of the cooled crucible, adjacent sectors Since the metal material flowing into the gap is prevented from increasing the tensile force between the cooling crucible and the ingot, cracks are not generated on the casting surface of the ingot.

In addition, in the case of a cooling crucible with the above structure, there is no need to significantly change the horizontal cross-sectional shape of the inside of the upper region and lower region, which are involved in heat removal during solidification, in the height direction (casting direction). , a significant decrease in the amount of heat removed does not occur. Therefore, even if high-speed casting is performed, the occurrence of double skin or breakout can be prevented.

EXAMPLES Furthermore, the present invention will be explained in more detail based on examples.

A continuous metal melting and casting apparatus according to the present invention having the structure shown in FIGS. 1 and 2, and a continuous metal melting and casting apparatus according to the present invention having the structure shown in FIGS. 1 and 3. The effects of the present invention were evaluated using the following methods.

In addition, FIG. 2 shows A- of the cooling crucible 2 used in this example.
FIG. 3 shows a schematic perspective view of a portion viewed from arrow A, FIG. 3 shows a schematic perspective view of a portion viewed from arrow A-A of another cooling crucible used in this example, and FIG. 2 shows the depth of the groove 21. FIG. 3 shows a cooled crucible in which the depth of the groove 21 is increased along the casting direction.

In Figure 1, crucible 2 has an inner diameter of 60 mm and an outer diameter of 100 mm.
It has dimensions lIm and height 1801, and is made of copper material.

Upper region 2 of cooled crucible 2 without sector structure
A is a hollow body having a height of 501 Ill and having a cooling water outlet 2d, and has a structure through which the cooling water can pass.

In this embodiment, the upper region 2b of the cooling crucible 2 having a sector structure is divided into 16 internal water-cooled sectors 2g.
It is a structure consisting of li! # between sector tonneaus that are in contact with s
2h + (7) upper Fifte 0.2 rtns, lower ite 0
．． 4 mN, height is 50III11.

The lower region 2C of the cooled crucible 2 is a hollow cooling body with an outer diameter of 200 N11l and a height of 80 m5 having a water supply port 2e, and a radius of 0.3 mtm on the inner surface of the wall of the cooled crucible 2.
A groove having a semicircular cross section with a height of 801 is provided on the extension (below) of the gap between adjacent sectors.

The inductor 7 has a structure in which a copper coil having a wall thickness of 2 mm and an outer diameter f 2 m+w is spirally wound four times around the cooling crucible 2 with an average diameter of 120 +ll++.

Further, above the cooled crucible 2, there is provided a bar for supplying the metal material 4, and below the cooled crucible 2, there is provided a pulling device for pulling out the cast ingot 6 downward. A pull-out rod 5 is provided.

The main parts of the continuous metal melting and casting apparatus according to the present invention having such a structure are housed inside the chamber 1.

Melting and casting operations were performed as follows.

First, after creating an Ar gas atmosphere in the chamber 1, the drawing rod 5 is inserted into the cooling crucible 2, and the titanium base material attached to the upper end of the drawing rod 5 is placed so that its upper part is at the middle of the height of the induction coil. It was placed so that it was positioned at

Next, a high frequency current of 150 - is applied to the inductor 7, and when the top of the molten titanium reaches a position corresponding to the upper part of the inductor 7, the pull bar 5 is lowered at a speed of 1.6 cm/min. At the same time, 200 g/win from the vibration feeder
supplied titanium material.

This operation was continued for 36 minutes, and the diameter was 581 mm.
A titanium ingot with a length of 576 mm and a weight of 6.5 kg was manufactured and its chemical composition was investigated.

As a result, the apparatus shown in FIGS.
With any of the apparatuses shown in Figures and Figure 3, a high-purity titanium ingot with an oxygen content of 2 (10 ppm), a carbon content of 230 ppm, a nitrogen content of 105 ppm, a copper content of 120 ppm or less, and the balance titanium can be obtained. Ta.

Moreover, the surface quality was also extremely good.

(Effects of the Invention) As detailed above, the present invention solves the problem of material contamination caused by the presence of slag, the problem of increased process due to stripping of the slag film, and the problem of cracks occurring on the casting surface of the ingot. was able to provide a continuous metal melting and casting device that can solve the problem of double skin and breakout occurrence when casting at high speeds.

Therefore, metal melting and continuous casting can be performed at high speed without using slag agents.

Furthermore, it is possible to produce a high-quality ingot with high purity and excellent surface properties.

The significance of the present invention having such effects is extremely significant.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing the overall configuration of the continuous metal melting and casting apparatus according to the present invention; and FIGS. 2 and 3 are A-A of the cooling crucible used in the examples, respectively. FIG. 3 is a three-dimensional diagram of a schematic perspective view showing a portion seen by arrows. 1: Chamber 1a: Chamber exhaust port 2: Crucible 2a: Crucible upper region 2b without sector structure;
Crucible upper region 2c with sector structure: Crucible lower region 2d with groove structure: Crucible cooling water outlet 2e: Crucible cooling water inlet 2f: Crucible cooling water passage 2a Sector 2h in crucible upper region: In crucible upper region Gap 21: Groove in the lower region of the crucible 3: Metal material in molten state 4: Metal material 5: Drawing rod 6: Ingot 7: Inductor

Claims (3)

[Claims] (1) A device that continuously melts and casts solid metal supplied from above, including a conductive cooling crucible in which a portion of the wall in the height direction is divided into a plurality of sectors;
A metal inductor having a coil-shaped inductor arranged to surround a part of the outer peripheral surface of the cooling crucible in the height direction, and a device for pulling the ingot cast in the cooling crucible downward. a continuous melting and casting apparatus, wherein said cooled crucible (i) is divided into said sectors;
(ii) a lower region that is provided following the upper region and is not divided into sectors; Continuous melting and casting equipment. (2) The continuous metal melting and casting apparatus according to claim 1, wherein the lower region further has a groove on an inner wall surface facing the ingot on an extension of the interval between the adjacent sectors. (3) Continuous melting and casting of metal according to claim 1 or 2, further comprising a chamber that separates the cooling crucible, the inductor, the raw material supply device, and the drawing device from the atmosphere. Device.