JPH0518676A - Continuous outflow control method for molten material - Google Patents

Abstract

PURPOSE:To obtain the continuous outflow control method of molten material, which is capable of controlling the outflow amount of the molten material in a crucible by a fine unit and supplying it to the next process of molding, granulating and the like. CONSTITUTION:The outflow port 4 of molten material 6 is provided on the bottom of a crucible 1 while metallic magnetism shielding plates 3 are arranged below the outflow port 4. The position of the magnetic shielding plate 3 is regulated to control an electromagnetic force to the molten material 6 in the crucible 1 and control the retaining force of the molten material 1 whereby the outflow amount of the molten material 6 through the outflow port 4 is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a metal / crude crucible.
It relates to continuous melting of materials such as semiconductors and ceramics, and continuous outflow control of molten materials.

[0002]

2. Description of the Related Art Usually, melting of metals and the like is carried out using a container such as a crucible made of refractory. For this reason, it is impossible to avoid contamination of the material from the refractory and the like, and it has been difficult to manufacture a highly pure material.

In recent years, as a method of melting a material requiring high purity, a technique of melting the material in a non-contact manner with a crucible wall by induction melting using a low temperature crucible (cold crucible) has been widely reported. In this low temperature crucible technology, materials such as metals are most suitable for induction melting in the high frequency region and the intermediate frequency region.

In this low temperature crucible, segments each having a crucible wall divided into a plurality are connected in an annular shape.
Each segment is made of copper having a hollow inside for passing cooling water. A material to be melted is put in the crucible, and a high frequency or intermediate frequency current is applied to the induction coil around the outer circumference of the crucible. Therefore, when a high-frequency current is passed through the coil, an eddy current is generated in the material inside the crucible, and heat is generated due to the eddy current loss. In addition, the electromagnetic force generated by the eddy current generated on the crucible surface and the eddy current generated on the melt surface can make the melt in the crucible non-contact with the crucible wall, and squeeze the wall below the crucible. The internal melt can be floated and dissolved. This allows the high-purity material to be dissolved from the crucible without contaminating it. A melting / crystallization method using this low temperature crucible technique is disclosed in Japanese Patent Laid-Open No. 60-28.
No. 76 publication. Further, a continuous casting method for silicon using this low-temperature crucible technique is disclosed in Japanese Patent Laid-Open No. Sho 64-64.
It is disclosed in Japanese Patent Publication No. 53732.

[0005]

In recent years, in order to obtain a highly pure material, there is an increasing demand for casting the material into an arbitrary shape or atomizing it. It is necessary to take it out in the molten state,
In the above-mentioned conventional method, the molten material in the crucible could not be discharged to the outside of the crucible in a trace amount.

The present invention provides a continuous outflow control method for a molten material in a crucible, which can be supplied to the next step such as molding and atomization while controlling the outflow amount of the molten material in the crucible in minute units.

[0007]

The first invention of the present invention is as follows:
In a method of inductively melting a material using a crucible and flowing out the molten material from an outlet provided at the bottom of the crucible, the electromagnetic force applied to the molten material in the crucible by a metal magnetic shield plate provided below the bottom of the crucible. A method for controlling the outflow of molten material in a crucible, characterized in that the outflow of molten material from the crucible is controlled by controlling force.

A second aspect of the invention is a method for supplying a material in a molten state to a crucible, adjusting the temperature in the crucible, and flowing out the molten material from an outlet provided at the bottom of the crucible. An induction current is made to flow through the molten material in the crucible by the installed coil, and the electromagnetic force applied to the molten material in the crucible is controlled by the metal magnetic shield plate provided below the bottom of the crucible, and the molten material flows out from the crucible. A method for continuously controlling the outflow of molten material in a crucible, characterized by controlling the temperature.

A third invention is characterized in that, in the first invention or the second invention, the crucible is a low temperature crucible.

[0010]

In the continuous outflow control method for molten material using the method of the present invention, the molten material in the crucible is held by the electromagnetic force and surface tension induced by the induction coil. By supplying the raw material to the molten material in the crucible through the opening in the upper portion of the crucible, the material is heated by the amount of heat of the molten material in the crucible and is quickly melted by the induction current induced by the induction coil. When the material is further supplied, the gravity overcomes the electromagnetic force and the surface tension supporting the molten material, so that the molten material flows out from the outlet provided in the lower part of the crucible. Here, the outflow amount can be controlled by changing the position of the metal magnetic shield plate provided below the crucible to control the electromagnetic force acting on the molten material in the crucible.

The metal magnetic shield plate is preferably made of a good electric conductor such as copper in order to suppress heat generation due to an induced current, and it is also desirable to cool the magnetic shield plate with cooling water or the like.

For the initial melting of the material, a material having a size capable of induction melting may be prepared and melted by an induction current,
A heating element such as graphite may be inserted into the material to generate heat by an induction current to melt the material, or a separately melted molten material may be supplied to the crucible.

The material continuously supplied to the crucible may be in the form of powder, in the form of lumps, or in advance of molten material which has been melted.

Usually, the crucible used for this melting is a low temperature crucible, but this low temperature crucible is made of copper from the viewpoint of thermal conductivity and electrical conductivity. Since the molten material can be brought into non-contact with the crucible wall, the crucible wall can be kept at a low temperature even when the temperature of the molten material is equal to or higher than the melting point of copper. However, when melting a material that affects the quality of the product as an impurity even if a trace amount of a metal element such as copper is used, just in case, the crucible wall may be coated with quartz glass or the interior of the crucible may be made of quartz. Good.

The diameter d of the outlet provided at the bottom of the low temperature crucible must be larger than that of the low temperature crucible used for floating melting. In the case of a normal low temperature crucible, the static pressure of the material must be supported by the surface tension so that the molten material does not flow out from the outlet provided at the bottom even in the absence of electromagnetic force. Therefore, the diameter of the outlet is designed to satisfy the condition of the expression (1). 2σ / d> ρgh + ρgd / 2 (1) (surface tension of material) (static pressure of material) where σ; surface tension of material [dy
n / cm] ρ; density of material [g / cm ³ h; head height of material in crucible [cm] g; gravitational acceleration g = 980 cm / s ^{2 When a} low temperature crucible is used in the present invention, the bottom of the crucible is used. In order to let the molten material flow out from the outlet of (2), the outlet diameter is designed to satisfy the condition of the equation (2). 2σ / d <ρgh + ρgd / 2 (2) In a low temperature crucible, surface tension and electromagnetic force generated from a coil are forces that support the molten material. Therefore, in the low-temperature crucible of the present invention, the holding amount of the molten material in the crucible can be adjusted and the flow rate can be controlled by adjusting the holding force of the electromagnetic force generated from the coil with the magnetic shield plate.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, a crucible 1 having a diameter of 25 mm divided into six segments made of copper is provided with an outlet 4 having a diameter of 3 mm. Each segment is provided with a flow path 8 through which cooling water flows to cool the crucible. A coil 2 is installed on the outer periphery of the crucible 1,
It is connected to a high frequency oscillator (not shown) via a power supply line 5. Below the crucible 1, a water-cooled copper ring-shaped magnetic shield plate 3 is installed. A material 6 in a molten state is held in a crucible 1 by an electromagnetic force generated by a coil 2. When the solid material 7 is supplied to the upper part of the opening of the crucible 1, the outflow port 4 provided at the bottom of the crucible 1
The molten material 6 flows out from the. By moving the position of the magnetic shield plate 3 up and down, the electromagnetic force applied to the molten material 6 can be adjusted to control the flow rate, and the molten material is controlled and flows out.

Continuous melting and continuous outflow of silicon were performed using the above apparatus. 200kH from high frequency oscillator to coil 2
An electric current of z was applied to hold 50 g of molten silicon. When 100 g of raw material silicon having an average particle diameter of 1 mm was supplied per minute, it was possible to stably flow out from the outlet 4 at the bottom of the crucible 1. At this time, when the position of the magnetic shield plate 3 was changed, the flow rate could be controlled according to the position of the magnetic shield plate 3. The temperature of the molten silicon at this time was 1500 ° C. The power applied to coil 2 in this device was 20 kW.

FIG. 2 shows an example in which the present invention is applied to a quenching thin film manufacturing process of stainless steel. In this process, there are two low temperature crucibles, the upper crucible 9 melts the solid raw material 7, and the molten material 6 is supplied to the lower crucible 10 from the outlet 4 provided in the lower part. Below the lower crucible 10 is a water-cooled roll 11 that rotates at high speed.
Is installed, and the molten material 6 flowing out from the lower crucible 10 is made to flow down onto a water-cooled roll 11 to produce a rapidly quenched thin film 12 of stainless steel, which is wound up. In the upper crucible 9, the components are adjusted while melting the stainless steel. In the lower crucible 10, temperature control and fine adjustment of the flow rate are performed.

FIG. 3 shows an embodiment in which the present invention is applied to titanium precision casting. Mold 13 under crucible 1
Is provided. Molten titanium 6 was injected into the mold 13 from the outlet of the bottom of the crucible 1 and the material was solidified in the mold 13 to obtain a titanium cast product having an arbitrary shape.

FIG. 4 shows an embodiment in which the present invention is applied to atomization of a titanium alloy. A nozzle 14 is provided which blows an inert gas onto the titanium alloy 6 in a molten state from the outlet of the outlet at the bottom of the crucible 1. By spraying an inert gas onto the flow of the molten titanium alloy 6 coming out of the crucible 1, the titanium alloy could be atomized and fine particles 15 of high purity titanium alloy could be obtained.

In the above embodiments, silicon and titanium alloys are used, but the present invention is also applied to other metals, semiconductors and ceramics.

[0022]

According to the continuous outflow control method for molten material in a crucible according to the present invention, a high-purity material free from contamination can be outflowed in a molten state from a crucible, and various steps such as casting and miniaturization are performed. It is possible to combine with, and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a diagram showing a continuous melting / continuous outflow device according to the present invention.

FIG. 2 is a diagram showing an example when the present invention is applied to a quenching thin film manufacturing process of stainless steel.

FIG. 3 is a diagram showing an example in which the present invention is applied to precision casting of titanium.

FIG. 4 is a diagram showing an example when the present invention is applied to atomization of a titanium alloy.

[Explanation of symbols]

1 copper crucible 2 coils 3 Magnetic shield 4 Outlet 5 power lines 6 Material in molten state 7 solid raw materials 8 Cooling water flow path 9 Upper crucible 10 Lower crucible 11 Water-cooled roll 12 Rapidly solidified thin film 13 Mold 14 nozzles 15 fine particles

Claims (3)

[Claims] 1. A method of inducing and melting a material by using a crucible and flowing out a molten material from an outlet provided at the bottom of the crucible, wherein a metal magnetic shielding plate provided below the bottom of the crucible is used to remove the melted material from the inside of the crucible. A continuous outflow control method for a molten material in a crucible, characterized by controlling an electromagnetic force applied to the molten material to control an outflow of the molten material from the crucible. 2. A method of supplying a material in a molten state to a crucible, adjusting the temperature thereof, and flowing out the material in a molten state from an outlet provided at the bottom of the crucible, wherein a coil installed on the outer periphery of the crucible Induction current is passed through the molten material, and the electromagnetic force applied to the molten material in the crucible is controlled by a metal magnetic shield plate provided below the bottom of the crucible, and the outflow of the molten material from the crucible is controlled. Continuous flow control method of molten material in crucible. 3. The continuous outflow control method for molten material in a crucible according to claim 1, wherein the crucible is a low temperature crucible.