JPS62107061A - Device for melting metal - Google Patents

Abstract

PURPOSE:To prevent the hole digging effect of a molten metal and to efficiently and safely melt and evaporate the metal in a crucible by monitoring the temp. of a crucible material and controlling a focusing coil to adjust the focus of an electron beam flux. CONSTITUTION:The electron ray flux 19 released from a filament 10 mounted to a filament power source is roughly adjusted in the beam flux width by a collimator 11 and is passed through an acceleration electrode 12, by which the energy thereof is amplified. The beam flux 19 is then deflected by a deflecting coil 13 and is finely adjusted by the focusing coil 14; thereafter, the beam flux bombards and heats the molten metal 2 in the crucible 1. The electron beam flux 19 is changed over to a small focus beam and large focus beam by a control circuit 5 via a driving circuit 8 for adjustment and a magnetic field generating power source 9. The focus of the flux 19 is adjusted or the bombardment and heating is stopped by the circuit 5 when the temp. increase of the crucible 1 is detected by a sensor 3 embedded in the crucible 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal melting apparatus that continuously melts and vaporizes metal in a vacuum space, such as in vacuum evaporation or isotope separation technology.

[Technical background of the invention and its problems] The method of melting metal by electron impact heating accelerates thermionic electrons emitted from a filament (hot cathode) heated to a high temperature with a high voltage, and then transfers them to a heated object. The kinetic energy of the electrons is converted into thermal energy, which heats and melts the metal. This electron impact heating method is used for various purposes because the heating temperature can be easily controlled and high energy density can be obtained, allowing high temperatures to be obtained and melting of high melting point metals.

However, when applying this electron impact heating method to equipment that melts and vaporizes metal continuously over a long period of time or to large-scale plant-level equipment, there are the following problems.

(1) On the melting surface of the metal to be melted, melting progresses from the focal point of the electron flux, so the focal point where the energy density is high is inevitably dug deep, while the surrounding area remains. ' occurs and efficient metal melting cannot be performed.

(2) If this drilling phenomenon progresses to an extreme extent, the crucible material will be directly impacted and heated, increasing the temperature of the crucible material and causing high-temperature corrosion with the metal to be melted, or shortening the life of the crucible. There is a risk of damage to the crucible.

(3) Due to the problems in items (1) and (2) above, the application of the electron impact heating method to ``a device or system that continuously obtains a large number of molten metal vapors using a large-capacity crucible'' is not suitable for molten metal. Maintenance was poor in terms of replenishment and crucible inspection, and it was not considered to be effective in terms of safety.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and it is possible to prevent the "burrowing effect" of the metal to be melted and to uniformly and efficiently distribute the metal to be melted in the crucible. It is an object of the present invention to provide an apparatus for melting metal by electron beam impact heating, which can melt metal safely and can be effectively applied to large-scale equipment.

[Summary of the invention] The present invention includes a collimator that adjusts the spread of the electron beam irradiated to the metal to be melted, and a focusing coil that adjusts the size of the focal point of the electron beam on the melting surface of the metal to be melted. By controlling the focusing coil, the metal to be melted is melted and vaporized by heating and melting with a thin electron beam flux (small focus beam) and continuously or periodically switching between a thick electron beam flux (large focus beam) and melting into the crucible. This metal melting apparatus is equipped with a temperature sensor and is configured to perform the above control while monitoring abnormal temperature rises in the crucible material.

[Embodiment j of the invention j Hereinafter, an embodiment of the metal melting device according to the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 is a crucible containing a metal to be melted 2,
A temperature sensor 3 is embedded within the crucible 1. This temperature sensor is connected to the input side of the control circuit 5 via a signal line 4. An electron acceleration power source 6, a filament power source 7, an adjustment drive circuit 8, and a magnetic field generation power source 9 are connected to the output side of the control circuit 5. A filament 10 as a hot cathode is attached to the filament power source 7, and the filament 10
A collimator 11 and an accelerating electrode 1 are provided between the crucible 1 and the crucible 1.
2. A deflection coil 13 and a focusing coil 14 are arranged in sequence. Note that the deflection coil 13 and the focusing coil 14
are arranged in two stages, each with a magnetic field generation power source 9 and a signal line 1.
5.16. In addition, the adjustment drive circuit 8
A fine adjustment motor 17 is provided between and the collimator 11, and the electronic acceleration power source 6 and the acceleration electrode 12 are connected by a signal line 18.

Here, an electron beam 19 is generated and accelerated by the filament power supply 7, the filament 10, the acceleration electrode 12, and the electron acceleration power supply 6. Collimator 1
Reference numeral 1 performs aperture adjustment of the electron beam bundle 19, and is activated by an instruction signal from the adjustment drive circuit 8.

The deflection coil 13 prevents the filament from being contaminated and deteriorated by molten metal vapor. Further, the focusing coil 14 performs flux adjustment (focus adjustment) of the electron beam on the metal melting surface.The deflection coil 13 and the focusing coil 14 are operated by the magnetic field generating power source 9. The temperature of the metal to be melted 2 accommodated in the metal melting crucible 1 is measured by a temperature monitoring sensor 3. Note that the control circuit 5 controls the overall operation of the electron beam ms heating method in the present invention.

That is, basically, the electron beam flux 19 is generated and emitted from the filament 10, and its energy is amplified when it passes through the accelerating electrode 12. Then, the metal to be molten 2 is impact-heated by being directed by the deflection coil 13 . In the present invention, as described above, in order to efficiently melt metal, switching control of the electron beam flux is performed on the impact heating surface. A beam adjusting collimator 11 and a focusing coil 14 are installed to perform this control.

The collimator 11 serves to roughly adjust the beam width at the generation part of the electron beam 19, and the focusing coil 14 finely adjusts the beam focus on the gold Ii1 melting surface by a combination of two pieces as shown. be.

Both are operated by the control circuit 5 programmed via the respective adjustment drive circuits 8 and magnetic field generation power sources 9,
The percussion heating by a thin electron beam bundle and a thick electron beam bundle is switched continuously or periodically.

Furthermore, in order to perform this switching control safely, the crucible 1 is equipped with a temperature sensor 3 for temperature monitoring, and is constantly monitored during impact heating. If the control circuit 5 detects and recognizes an abnormal temperature rise in the crucible 1 based on a signal from the temperature sensor 3, the focus of the beam is readjusted or the impact heating is stopped.

That is, as shown in the figure, the solid line 20 indicates that the "burrowing effect"'21 occurs by continuously performing electron beam impact heating with a narrow electron beam flux having high energy density and high dissolving ability. In order to overcome this, break a
As shown in 23, it is necessary to irradiate a thick beam of electron beams to the bamboo that has the "burrowing effect" 21 to the depths, melting the surrounding area evenly and smoothing the melted surface.When using a thick beam of electrons Since the energy density is lower, the dissolving ability is lowered, but it is very effective in preventing the digging effect.

Therefore, the metal 2 in the crucible 1 is left uniformly by switching continuously or periodically between impact heating of a thin electron beam bundle (small focus heating) and impact heating of a thick electron beam bundle (large focus heating) and controlling it safely. It can be melted and vaporized without soaking, making it possible to improve the efficiency of metal melting.

[Effects of the Invention] The metal melting apparatus using the electron impact heating method according to the present invention provides the following effects.

(1) Since the metal melting surface in the metal melting crucible (hearth) can be melted while smoothing, there is no residue left behind, and the efficiency of metal melting can be improved.

(2) The "drilling effect" can be prevented, and the risk of damage to the crucible due to direct heating is eliminated, so safety and reliability are improved.

(3) Since there is no abnormal temperature rise in the crucible, high-temperature corrosion that occurs between the crucible and the metal to be melted can be prevented, and the quality of the metal melting vapor is improved.

(4) Maintenance efficiency is improved because the number of times the crucible is replenished with molten metal and the number of times the crucible is inspected can be reduced and labor saved.

(5) Application to "a large-scale device or system that continuously obtains a large amount of molten metal vapor using a large-capacity crucible" is effective.

[Brief explanation of drawings]

The figure is a partial cross-sectional system diagram showing an embodiment of the metal melting apparatus according to the present invention.

Claims (1)

[Claims] (1) A crucible that accommodates the metal to be melted, a temperature sensor that measures the temperature of this crucible, a control circuit that inputs the signal of this temperature sensor, and an electronic acceleration power source that receives the output signal from this control circuit. It consists of a filament power supply/adjustment drive circuit, a magnetic field generation power supply, and a collimator/acceleration electrode/deflection coil and focusing coil arranged in sequence between the filament connected to the filament power supply and the crucible, and the acceleration electrode is used to accelerate the electrons. A metal melting apparatus characterized in that the collimator is connected to the adjustment drive circuit, and the deflection coil and the focusing coil are connected to the magnetic field generation power source.