JPH081281A - Method and apparatus for producing semi-solidified metallic material - Google Patents

Abstract

PURPOSE:To efficiently stir a semi-solidified metallic material in a low electric power by executing the stirring with an electromagnetic force by rotary magnetic field for shifting along the outer periphery of a cooling and stirring vessel at one side of an N pole or an S pole of an electromagnetic coil. CONSTITUTION:The stirring with the circular fluid is given by the rotary magnetic field generated with a rotary magnetic field generating device 4 and the metal is made to be the semi-solidified metallic slurry 15' containing primary crystal grains generated accompanied with the progress of the solidification and shifted downward and discharged to out of the apparatus as the semi-solidified metallic slurry flow 16 through a discharging nozzle 5. In the arrangement of the electromagnetic coil 4' in this rotary magnetic field generating device 4, a case of a four-pole and three- layer is shown in the attached figure, and the electromagnetic coil are arranged at 12 pieces in the radiating state at the outer peri phery of the cooling and stirring vessel composed of a cooling cylinder 2 and a water-cooling jacket 3. These electromagnetic coils 4' supply three-phase AC current through an electric powder converting device and the magnetic pole near the cooling and stirring vessel always becomes the N pole. The rotary magnetic field with these electromagnetic coils 4' is shifted in order to generate the electric power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semi-solid metal material which undergoes a process of forming a semi-solid metal slurry in which primary crystal grains are dispersed.
It proposes a manufacturing method and an apparatus therefor using an electromagnetic stirring system.

The term "semi-solidified metal material" as used herein refers to a rheo process in which a semi-solidified metal slurry is directly processed, that is, a thixograph in which the semi-solidified metal slurry is once cooled and solidified and then reheated to be processed in a semi-molten state. It is a useful material that is used for processing and forging processing in the solid state, and is capable of significantly improving material properties (workability, quality, etc.) and reducing costs.

[0003]

2. Description of the Related Art Although many methods for producing a semi-solidified metal slurry have been proposed, an electromagnetic stirring method is effective as an industrial scale production method. As a means for producing the semi-solidified metal slurry of this electromagnetic stirring system, for example, Japanese Patent Publication No.
There is a two-pole rotating magnetic field system disclosed in Japanese Patent Publication No. 25464 (method and apparatus for producing thixotropic metal slurry).

The main advantage of this two-pole rotating magnetic field system is that the electromagnetic force acts in the direction perpendicular to the growth direction of the dendrites when cooling the molten metal, so that it is efficient in cutting and dispersing the dendrites. Further, since magnetic flux passes through the central portion of the object to be stirred, the rotational force also acts on the central portion, so that there is no so-called dead zone. However, when increasing the diameter of the cooling / stirring tank in order to expand the production scale, in the case of the two-pole rotating magnetic field method, the magnetic flux density is attenuated as the pole spacing increases. Therefore, there is a problem that the power efficiency for stirring is lowered and the power amount must be increased more than necessary.

On the other hand, there is also a method of rotating the permanent magnet at a high speed on the outer circumference of the cooling / stirring tank, but the permanent magnet is thermally weak, and the adhesion and accumulation of dust such as iron powder is not easy to maintain. There is a problem and it is not practical.

[0006]

Therefore, the present invention advantageously solves the above-mentioned problems, and the electromagnetic stirring system favorably stirs with a low electric power even if the cooling / stirring tank is enlarged, and a solid-liquid mixed phase is obtained. An object of the present invention is to propose a method for producing a semi-solidified metal material capable of obtaining the semi-solidified metal slurry and the apparatus for producing the same.

[0007]

According to the results of experiments and studies by the inventors, as described above, in the two-pole rotating magnetic field system,
Along with the increase in size of the apparatus, that is, the increase in size of the cooling / stirring tank, there has been a problem that the pole spacing increases and the attenuation of the magnetic flux density increases and the power efficiency for stirring decreases.

Therefore, as a result of further experiments and examinations, 1. The solidification of the molten metal in the cooling / stirring tank progresses and primary crystal grains are generated near the inner wall surface of the cooling / stirring tank. A semi-solidified metal slurry in which grains are suspended is obtained, and
It is not necessary to apply an electromagnetic force to the central portion of the stirring tank to positively apply the stirring force to this portion.

2. If only the vicinity of the inner wall surface of the cooling / stirring tank is swirled strongly, appropriate flow is induced in the central portion as well. The semi-solidified metal slurry having a solid phase ratio of up to about 0.3, which is usually produced, has good fluidity, and swirl flow is also induced in the central portion. Etc.

Therefore, when the semi-solidified metal slurry is produced in the cooling / stirring tank for cooling from the outer circumference, the electromagnetic stirrer arranged on the outer circumference of the cooling / stirring tank does not need to be a two-pole rotating magnetic field system, but rather the apparatus. Considering the increase in size, the above-mentioned method, which has a gap between the gaps, is disadvantageous.

In view of the above, the present invention serves as an electromagnetic stirrer having good efficiency and suitable for increasing the size of the apparatus, so that an electromagnetic force for stirring is applied near the inner wall surface of the cooling / stirring tank. is there.

That is, the gist of the present invention is as follows. A semi-solid metal that undergoes a process in which a molten metal supplied from above a cylindrical cooling / stirring tank is made into a solid-liquid mixed-phase semi-solid metal slurry in which granular primary crystals are suspended by cooling with stirring by electromagnetic force. In the method of manufacturing a material, a semi-solid metal material characterized in that stirring by electromagnetic force is performed by a rotating magnetic field that is moved along the outer circumference of a cooling / stirring tank by either one of the N pole or S pole of the electromagnetic coil. In the above, the stirring by electromagnetic force can be a swirling flow between the cooling / stirring tank and the core arranged in the cooling / stirring tank. A semi-solid metal that undergoes a process in which a molten metal supplied from above a cylindrical cooling / stirring tank is made into a solid-liquid mixed-phase semi-solid metal slurry in which granular primary crystals are suspended by cooling with stirring by electromagnetic force. In a material manufacturing apparatus, a rotating magnetic field is generated in which one of N poles or S poles of a plurality of electromagnetic coils radially arranged on the outer circumference of a cooling / stirring tank sequentially moves along the outer circumference of the cooling / stirring tank. An apparatus for manufacturing a semi-solidified metal material, which comprises an apparatus, wherein a core is placed in a cooling / stirring tank, and the core is movable in the vertical direction to the cooling / stirring tank. It can be inserted and retracted. The core is preferably arranged coaxially with the cooling / stirring tank.

It is preferable that the core of the apparatus for producing a semi-solidified metal material in the item (1) is made of a non-magnetic material.

The cooling / stirring tank of the apparatus for producing a semi-solidified metal material according to the item 1 or 2 is made of a non-magnetic metal having a low thermal conductivity, a non-magnetic metal containing a refractory sleeve, and an austenitic stainless steel. It is preferable that it is made of steel, made of austenitic stainless steel containing an alumina sleeve, or made of austenitic stainless steel containing an alumina / graphite sleeve.

[0015]

The function and effect of the present invention will be described below. This invention is a process for forming a semi-solid metal slurry in which granular primary crystals are suspended by electromagnetically stirring a molten metal in a cylindrical cooling / stirring tank under cooling, for rheo processing, for thixo-processing. In producing a semi-solid metal material suitable as a material for forging, electromagnetic stirring is applied to the N pole or S pole of the electromagnetic coil.
The essence is that either one of the poles is performed by a rotating magnetic field that moves along the outer circumference of the cooling / stirring tank, and by doing so, the electromagnetic force is the molten metal or semi-solid metal near the inner wall of the cooling / stirring tank. The slurry acts intensively and swirls them to perform agitation, and efficient agitation with low power consumption regardless of the size of the device, that is, the diameter of the cooling / stirring tank increases. You can

Further, when the core is placed in the cooling / stirring tank, the molten metal or the semi-solidified metal slurry to be swirled is excluded from the central core portion, so that the electromagnetic force is kept in the cooling / stirring tank. The electromagnetic agitation method of the present invention, in which the magnetic field is concentrated near the wall surface, becomes more efficient.

The semi-solidified metal slurry produced in the cooling / stirring tank may be directly subjected to rhe processing.
It is also possible to supply it to a mold or a continuous casting machine to cast it into a slab and then subject it to thixoforming or casting.

Next, in the apparatus for producing semi-solidified metal slurry, the electromagnetic stirrer, that is, the rotating magnetic field generator, has a plurality of electromagnetic coils radially arranged on the outer periphery of the cooling / stirring tank, and magnetic poles close to the cooling / stirring tank are provided. Either the N pole or the S pole may be set, and the electromagnetic coils may be sequentially moved to the adjacent electromagnetic coils to supply power to the electromagnetic coils.

In the above description, power is supplied to the electromagnetic coil by using, for example, a direct current power source or an alternating current power source through a power conversion device, and the pole of the electromagnetic coil near the cooling / stirring tank is always constant. The electric power may be supplied by sequentially moving the magnetic coils adjacent to each other in the direction of rotating the magnetic field so that Further, the number of magnetic poles may be one, but it is preferable to appropriately select it within a range that is facility-friendly.

The cooling / stirring tank is preferably non-magnetic so as to prevent the attenuation of the magnetic flux density. Further, when the solidified shell grows on the inner wall surface of the cooling / stirring tank, the attenuation of the magnetic flux density due to the solidifying shell poses a problem.Therefore, the heat removal rate is controlled to suppress the growth of the solidifying shell, that is, the cooling / stirring tank. It is preferable to appropriately reduce the thermal conductivity of.

As such a cooling / stirring tank, it is preferable to use, for example, austenitic stainless steel or austenitic stainless steel containing a refractory sleeve such as alumina or alumina brafite.

Although the core is not greatly affected by its positional relationship, it is preferably made non-magnetic in order to prevent the attenuation of electromagnetic force.

As described above, according to the present invention, the electromagnetic stirring system is not the two-pole rotating magnetic field system in which the magnetic flux passes through the center of the cooling / stirring tank, but either the N pole or the S pole is cooled / stirring tank. Since a rotating magnetic field system that rotates along with the semi-solidified metal slurry is used, the molten metal or semi-solidified metal slurry near the inner wall surface of the cooling / stirring tank can be strongly swirled by applying an electromagnetic force to the semi-solidified metal slurry. It can be manufactured with electric energy. This effect becomes more remarkable as the device becomes larger. Further, when the core is used, the molten metal or the semi-solidified metal is structurally present in the vicinity of the inner wall surface of the cooling / stirring tank, and it suffices to flow these, so that the significance of the present invention is more remarkably expressed.

Since the present invention uses the electromagnetic coil, even if iron powder or dust adheres during operation, it is easy to remove them, and as in the case of using a permanent magnet, the adhered matter can be removed. However, since the electromagnetic coil can be installed in the water-cooled Box and is strong in terms of heat, the stirring force will not be weakened by raising the temperature as compared with the permanent magnet.

Further, by using a cooling / stirring tank which is non-magnetic and has an appropriately small thermal conductivity, the magnetic flux density is prevented from being attenuated due to the growth of the apparatus and the solidification shell, and strong stirring is performed without reducing the stirring force. Can be maintained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of a semi-solidified metal slurry manufacturing apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is an explanatory view of an apparatus for producing a semi-solidified metal slurry by the electromagnetic stirring method. In FIG. 1, a cooling / stirring tank that is non-magnetic and appropriately small in heat conduction comprises a cooling cylinder 2 and a water cooling jacket 3, and a rotating magnetic field generator 4 having a power source 14 is installed on the outer periphery of the cooling / stirring section. ing.
Then, the cooling water 13 is supplied from the lower part of the cooling / stirring tank, passes through the outer surface of the cooling cylinder 2 and is drained (13 ') from the upper part,
The molten metal 15 supplied is given an appropriate cooling effect.

A tundish 1 lined with a refractory material 1'is connected to the upper end of the cooling / stirring tank, and a discharge nozzle 5 is provided at the bottom. A non-magnetic core 6 is arranged at the center of the cooling / stirring tank, and the core 6 is rotatably supported by a support arm 8 via a bearing 7. The support arm 8 is hydraulically supported by a support base 11. It is mounted so as to be able to move up and down through a lifting means such as a cylinder 12 so that it can be inserted into the cooling / stirring tank and retracted from the cooling / stirring tank.
By adjusting the gap distance between the discharge nozzle 5 and the discharge nozzle 5, the discharge speed and the solid phase ratio of the discharged semi-solidified metal slurry are controlled. Further, the core 6 is connected to a torque meter 10 so that the operating condition can be checked by measuring the torque.

In the production of the semi-solidified metal slurry with this apparatus, the molten metal 15 is continuously supplied to the tundish 1 so that the molten metal 15 flows into the cooling / stirring tank.
This molten metal 15 is appropriately cooled in a cooling / stirring tank, and is stirred by a rotating magnetic field generated by the rotating magnetic field generator 4 by swirling flow, and a semi-solidified metal slurry containing primary crystal grains generated as solidification progresses. 15 'and moves downward, and through the discharge nozzle 5, the semi-solidified metal slurry flow 1
6 is discharged out of the apparatus.

On the other hand, FIG. 2 is an explanatory view of the arrangement of electromagnetic coils and the rotating magnetic field generating mechanism of the rotating magnetic field generating device. 2 (a), (b), and (c) show the case of four poles and three phases, in which 12 electromagnetic coils 4'are radially arranged on the outer circumference of a cooling / stirring tank composed of a cooling cylinder 2 and a water cooling jacket 3. Individually arranged. These electromagnetic coils 4 ′ are cooled by supplying 3-phase alternating current through a power converter (not shown).
The magnetic pole close to the stirring tank is always N pole.
The dotted lines in the figure indicate the lines of magnetic force.

The rotating magnetic field generated by these electromagnetic coils 4'is
At the time of T ₁ , the following T is applied to the φ ₁ electromagnetic coil 4'of (a).
_{At 2} o'clock, it is generated by supplying electric power to the φ ₂ electromagnetic coil 4'of (b) and at T ₃ by sequentially moving to the φ ₃ electromagnetic coil 4'of (c).

Next, the result of producing a semi-solidified metal slurry using the apparatus shown in FIGS. 1 and 2 will be described.

In the above, in the cooling / stirring tank,
Inner diameter: 220 mmφ SUS304 cylinder, thickness: 10
A cooling cylinder 2 having a mm-mm refractory sleeve made of alumina / graphite and a water cooling jacket 3 made of SUS304 were used, and a core 6 made of alumina / graphite having an outer diameter of 100 mmφ was used.

Al-10mas melted by heating to an appropriate temperature
A molten metal 15 of s% Cu alloy is supplied to a cooling / stirring tank through a tundish 1, and a rotating magnetic field is applied by a rotating magnetic field generator 4 under cooling through a water cooling jacket 3 to stir to obtain a semi-solidified metal slurry. The semi-solidified metal slurry 16 was continuously discharged from the discharge nozzle 5 at a discharge amount of 20 l / min by raising and lowering the core 6. The magnetic flux density on the inner wall surface of the cooling / stirring tank cooling cylinder was about 1000 gauss.

As a result, a semi-solidified metal slurry having a solid phase ratio of 0.25 could be continuously and stably produced.

Further, the semi-solidified metal slurry 16 was discharged under the same conditions as above except that the core 6 was retracted.
As a result, the central part of the free surface of the molten metal in the cooling / stirring tank became large, but a semi-solid metal slurry with a solid phase ratio of 0.20 was continuously and stably produced at a discharge rate of 25 l / min. did it. In addition, in the apparatus scale shown in this embodiment, the power supply capacity of 700 KVA was required in the conventional method of the two-pole three-phase system, but according to the present invention, it is 500.
It was confirmed that equivalent stirring can be performed with KVA and a similar semi-solidified metal slurry can be produced.

[0037]

According to the present invention, in the production of a semi-solid metal material by electromagnetic stirring, electromagnetic stirring is performed by a rotating magnetic field in which either the N pole or the S pole of the electromagnetic coil moves along the outer circumference of the cooling / stirring tank. According to the present invention, it is possible to efficiently stir with a low electric power amount, and the effect becomes more remarkable in response to the expansion of the production scale, that is, the enlargement of the apparatus. It greatly contributes to cost reduction of materials.

[Brief description of drawings]

FIG. 1 is an explanatory view of a semi-solidified metal slurry by an electromagnetic stirring method.

FIG. 2 is an explanatory view of an arrangement of electromagnetic coils and a rotating magnetic field generating mechanism of a rotating magnetic field generating device according to the present invention.

[Explanation of symbols]

 1 Tundish 1'Refractory material 2 Cooling cylinder 3 Water cooling jacket 4 Rotating magnetic field generator 4'Electromagnetic coil 5 Ejection nozzle 6 Core 7 Bearing 8 Support arm 9 Connecting shaft 10 Torque meter 11 Support 12 Hydraulic cylinder 13 Cooling water (water supply) ) 13 'Cooling water (drainage) 14 Power supply 15 Molten metal 15' Semi-solidified metal slurry 16 Discharged semi-solidified metal slurry

Front Page Continuation (72) Inventor Tsuji Shinji 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture, within Reotech Co., Ltd. (72) Inventor Isamu Hironaka 1, Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture, within Reotech Co., Ltd.

Claims (11)

[Claims] 1. A process in which a molten metal supplied from above a cylindrical cooling / stirring tank is stirred by electromagnetic force under cooling to form a solid-liquid mixed phase semi-solid metal slurry in which granular primary crystals are suspended. In the method for producing a semi-solidified metal material, the stirring by electromagnetic force is performed by a rotating magnetic field in which either the N pole or the S pole of the electromagnetic coil moves along the outer circumference of the cooling / stirring tank. A method for producing a semi-solid metal material. 2. Stirring by electromagnetic force comprises a cooling / stirring tank,
The method for producing a semi-solid metal material according to claim 1, wherein the flow is a swirling flow between a core arranged in the cooling / stirring tank. 3. A process in which a metal melt supplied from above a cylindrical cooling / stirring tank is stirred by electromagnetic force under cooling to form a solid-liquid mixed phase semi-solid metal slurry in which granular primary crystals are suspended. In the apparatus for manufacturing a semi-solidified metal material, the N pole or the S pole of a plurality of electromagnetic coils radially arranged on the outer circumference of the cooling / stirring tank is sequentially arranged along the outer circumference of the cooling / stirring tank. An apparatus for manufacturing semi-solid metal materials, which is equipped with a moving rotating magnetic field generator. 4. An apparatus for producing a semi-solid metal material according to claim 3, wherein a core is arranged in the cooling / stirring tank. 5. A core which is vertically movable and is insertable / retractable with respect to the cooling / stirring tank.
An apparatus for producing a semi-solid metal material according to. 6. The apparatus for producing a semi-solid metal material according to claim 4, wherein the core is made of a non-magnetic material. 7. The apparatus for producing a semi-solid metal material according to claim 3, 4, 5 or 6, wherein the cooling / stirring tank is made of a non-magnetic metal having a small thermal conductivity. 8. The apparatus for producing a semi-solid metal material according to claim 3, 4, 5 or 6, wherein the cooling / stirring tank is made of a non-magnetic metal containing a refractory sleeve. 9. The apparatus for producing a semi-solid metallic material according to claim 3, 4, 5 or 6, wherein the cooling / stirring tank is made of austenitic stainless steel. 10. The apparatus for producing a semi-solid metal material according to claim 3, 4, 5 or 6, wherein the cooling / stirring tank is made of austenitic stainless steel containing an alumina sleeve. 11. The apparatus for producing a semi-solid metal material according to claim 3, 4, 5 or 6, wherein the cooling / stirring tank is made of austenitic stainless steel having an alumina / graphite sleeve inside.