JP2013052407A - Apparatus for supplying molten metal to die-casting machine, and method for supplying the molten metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a holding furnace.SOLUTION: An apparatus for supplying a molten metal to a die-casting machine includes: a crucible 20; and a plasma melting furnace 50 for melting solid metal mass that are cast into the crucible 20 to obtain the molten metal by irradiating the solid metal mass with plasma arc, which then is higher in temperature than a burner and is faster in melting rate. Therefore, the solid metal mass can be melted and the resultant molten metal can be supplied to the die-casting machine according to a production cycle, thus eliminating the holding furnace.

Description

  The present invention relates to a technique for melting a metal lump and supplying it to a die casting machine.

  In the transport machinery industry such as automobiles, a lot of aluminum (hereinafter simply referred to as “aluminum”) is used for weight reduction. In general, the aluminum lump is melted in a central melting furnace in a die casting factory, and the molten aluminum is kept warm in a holding furnace. Or, a lump of aluminum is melted in a central melting furnace (high heat burner method) set up in a melting factory different from the die casting factory, and the molten aluminum is transported from the melting factory to the die casting factory by a heat insulating car. It is kept warm in the holding furnace. And according to the production cycle of a die-casting machine, molten aluminum is supplied from a holding furnace (the following patent document 1 etc.). For this reason, even when it is not necessary to supply molten aluminum, heating is necessary to maintain the temperature of the molten metal, which is wasteful in terms of energy.

JP-A-6-320248

  The present invention has been completed based on the above circumstances, and an object thereof is to stably supply a molten metal to a die casting machine as much as necessary when necessary, and to eliminate a holding furnace.

  The present invention is a supply device that melts a metal lump and supplies it to a die casting machine, and includes a container and a plasma melting device that irradiates a metal lump charged in the vessel with a plasma arc and melts the metal lump. .

  The present invention is a method for supplying a molten metal, which is irradiated with a plasma arc from a plasma melting device to melt the molten metal in the molten metal and supply it to a die casting machine.

  The plasma arc has a higher temperature and a higher melting rate than the burner. Therefore, for example, according to the production cycle, the metal lump can be melted and the molten metal can be supplied to the die casting machine. Therefore, the holding furnace can be eliminated.

The following configuration is preferable as an embodiment of the above invention.
-It has the hot water part formed in the lower part of the said container and pouring the said molten metal, and the opening-and-closing apparatus which opens and closes the said hot water part. An oxide film is formed on the surface of the molten metal by oxidation. Therefore, when the molten metal is transferred to the die casting machine side, if the molten metal is scooped from the upper surface side with a handle or the like, an oxide is mixed into the molten metal. In this respect, since the hot water discharge portion is formed at the lower portion of the container and the molten metal is drawn from the lower side of the container, there is little or no mixing of oxides with respect to the molten metal to be discharged. In addition, the lower part of a container said here means at least below the surface of a molten metal.

The opening / closing device is a rotary operation type cock having a cylindrical cock body. In this way, the operability is good and the molten metal is good.

The cross section of the cock body has a hollow shape. In this way, the heat capacity of the cock body is smaller than when the cross-sectional shape is a solid shape, so that the temperature of the molten metal is difficult to decrease. Therefore, it becomes possible to prevent re-solidification of the molten metal, and does not cause a defective hot water.

The plasma melting apparatus is an argon plasma melting apparatus using argon as a working gas. Since argon plasma does not contain oxygen, oxidation of the dissolved metal can be suppressed. In addition, if argon plasma is used, the plasma is easy to stabilize and turbulent flow is unlikely to occur, so that the oxide is prevented from being entrained in the molten metal.

The plasma melting apparatus has a tungsten electrode as an electrode for generating the plasma arc. When the electrode is made of carbon or copper, a part of the electrode may be melted and mixed into the molten metal. However, if the electrode is a tungsten electrode, the melting point is high and it is difficult to melt, so there is little or no fear of mixing.

・ Plasma arc is irradiated twice to the metal in the container at the time of melting the metal lump and at the time of tapping. In this way, even if the molten metal is re-solidified, it is melted again when the molten metal is discharged. Therefore, it does not cause poor hot water. The “metal in the container” includes a metal lump and a molten metal.

  According to the present invention, the metal lump is melted and fed directly to the die casting machine in accordance with the production cycle. As a result, the holding furnace can be eliminated. Moreover, it is possible to prevent re-solidification of the molten metal, and the molten metal can be stably supplied.

The block diagram which shows the system configuration | structure of the molten aluminum supply apparatus which concerns on Embodiment 1. FIG. Diagram showing the structure of molten aluminum (Showing the closing position of the cock body) Top view of cock body Cross section of cock body Diagram showing the structure of molten aluminum (showing the opening position of the cock body) Timing chart showing the hot water cycle The block diagram which shows the system configuration | structure of the molten aluminum supply apparatus which concerns on Embodiment 2. FIG. Diagram showing the structure of molten aluminum (Showing the closing position of the cock body) Timing chart showing the hot water cycle

  <Embodiment 1>

A first embodiment of the present invention will be described with reference to FIGS.
1. Overall Structure of Molten Aluminum Supply Device S The molten aluminum supply device S melts the aluminum metal lump U and supplies it directly to the die casting machine. The base portion 10, the carbon crucible 20, the plasma melting device 50, Is provided. Hereinafter, aluminum is simply referred to as aluminum.

  As shown in FIGS. 1 and 2, the upper surface of the crucible 20 is open, and a heat insulating material 27 is attached to the peripheral wall. The crucible 20 is installed adjacent to a die casting machine (not shown).

The platform 10 serves as a support for the crucible 20 and is composed of a metal block. A heat insulating material 27 is also attached to the outer periphery of the base 10 in the same manner as the crucible 20.
In addition, the material of the base part 10 is carbon, and the heat insulating material 27 is a high purity silica type heat insulating material.

  A mounting hole 23 is formed through the bottom wall 22 of the crucible 20. On the other hand, a convex fitting portion 12 is formed on the upper surface of the base portion 10 and is fitted into the mounting hole 23 of the crucible 20 without any gap from below.

  Thereby, the crucible 20 can be stably supported by the base part 10 without lateral displacement. A hot water outlet 15 is formed in the center of the base 10. The hot water outlet hole 15 extends in the vertical direction, and the upper end side of the hot water outlet hole 15 passes through the upper surface of the fitting part 12 and communicates with the inside of the crucible 22.

  As shown in FIG. 1, an argon plasma melting apparatus (hereinafter simply referred to as a plasma melting apparatus) 50 includes a plasma torch 51, an argon cylinder 61 for supplying argon gas as a working gas, a cooling tower 63, a pilot power supply 65, The main power supply 67 is provided.

  As shown in FIG. 2, the plasma torch 51 has a structure in which a tungsten electrode (cathode) 55 is built inside a cylindrical case 53, and the inside of the crucible 22 is arranged with the nozzle at the tip of the torch facing downward. To face. Inside the plasma torch 51, a flow path 56 of argon which is a working gas is formed. A copper electrode 57 is attached to the tip of the nozzle, and an arc is generated between the built-in tungsten electrode 55 and the copper electrode 57 at the tip of the nozzle by applying a DC voltage via a pilot power supply 65. A high temperature plasma arc (argon plasma arc) is irradiated from the tip of the nozzle. Thereby, the plasma arc can be irradiated to the aluminum metal block U in the crucible 20.

  The plasma melting apparatus 50 is configured to automatically switch the power source from the pilot power source 65 to the main power source 67 after a predetermined time has elapsed from the start of plasma arc irradiation. As shown in FIG. 2, the main power supply 67 is configured to apply a DC voltage between the electrode 70 attached to the bottom surface of the base 10 that supports the crucible 20 and the tungsten electrode 55 built in the case 53. Therefore, after switching, a DC voltage is applied between the tungsten electrode 55 and the aluminum metal block U via the main power supply 67, and the plasma arc is stably irradiated toward the metal block U. The Thereby, the aluminum metal lump U can be stably dissolved by the plasma arc. The plasma current generated by the plasma arc has a constant current characteristic and can be changed depending on the dissolution rate. The current is approximately 400 A, and the plasma voltage is determined by the length of the plasma arc and is approximately 70V. Therefore, the plasma power supply having the constant current characteristic and the load voltage of several hundred volts is optimal.

  The temperature of the plasma arc emitted from the plasma torch 51 is several thousand K (Kelvin), and the weight of the aluminum metal block U supplied to the crucible 20 is determined by the required die casting weight, but is 1 kg to 3 kg. A small amount. Therefore, it is possible to melt the aluminum metal lump U in an extremely short time. According to this molten aluminum supply device S, the molten aluminum U is discharged from the supply of the aluminum metal lump U in a short time of about 30 seconds. Is possible. The platform 10 and the crucible 20 are arranged adjacent to a die casting machine (not shown).

  Moreover, in this embodiment, the raising / lowering apparatus (not shown) which raises / lowers the plaza torch 51 is provided, the crucible is lifted up from the position of FIG. 2, and the upper surface of the crucible 20 is opened. The aluminum metal block U is thrown into 20. 2 is a temperature sensor, and is configured to detect the temperature of the base 10 and the crucible 20.

2. A molten metal aluminum pouring structure A pouring pipe 30 is accommodated in the base 10 that supports the crucible 20. The hot water discharge pipe 30 is made of carbon, and as shown in FIG. The hot water discharge pipe 30 penetrates the side surface of the base portion 10 and protrudes to the outside, and the tip of the pipe faces the upper side of the injection sleeve 80 on the die casting machine side. Further, an opening 33 is formed in the upper surface wall of the rear end portion of the tapping pipe 30 and is positioned so that the opening 33 is located just below the tapping hole 15 formed in the base portion 10.

  As a result, the molten aluminum U melted in the crucible 20 passes through the hot water hole 15 and the hot water pipe 30 in this order and is discharged into the injection sleeve 80 of the die casting machine. As described above, in the present embodiment, the molten aluminum melt is extracted from the bottom wall 22 side of the crucible 20 (outflow of hot water), so that the following effects can be obtained.

  An oxide film is formed on the surface F of the molten aluminum U by oxidation. For this reason, when the molten aluminum U is transferred to the injection sleeve 80 on the die casting machine side, if the molten aluminum U is drawn from the upper surface side with a handle or the like, oxides are mixed into the drawn aluminum molten metal. In this respect, since the molten metal hole 15 is formed in the bottom wall 22 of the crucible 20 and the molten aluminum U is extracted from the lower side of the container, there is little or no oxide mixed into the molten aluminum U to be discharged.

  A cock 40 that opens and closes the hot water outlet 15 is attached in the middle of the hot water outlet 15 that is a passage for the molten aluminum U. Specifically, as shown in FIG. 2, the hot water outlet 15 has a two-stage configuration, and the diameter of the lower hole 15 </ b> B connected to the hot water pipe 30 with respect to the upper hole 15 </ b> A communicating with the crucible 20. Is getting bigger. An arcuate arc surface 15C is formed at the boundary between the upper hole 15A and the lower hole 15B.

  The cock 40 includes a cock body 41. As shown in FIG. 3, the cock body 41 has a configuration in which a hollow semicircular arc-shaped opening / closing part 43 is provided at the tip of a hollow cylindrical body 42. And the cock main body 41 is attached with respect to the base part 10 so that rotation operation is possible, fitting the arc-shaped opening-and-closing part 43 inside the circular arc surface 15C of the hot-water hole 15.

  The front end portion 42A of the body portion 42 of the cock main body 41 is drawn to the outside of the base portion 10, and the cock main body 41 can be rotated along the axis L by operating the drawn front end portion 42A. By this rotation operation, the arc-shaped opening / closing part 43 can be displaced between a closed position (position for closing the hot water hole 15) shown in FIG. 3 and an open position (position for opening the hot water hole 15) shown in FIG. Accordingly, by displacing the arc-shaped opening / closing portion 43 from the closed position shown in FIG. 3 to the opening position shown in FIG. 5, the molten aluminum U can be discharged to the injection sleeve 80, and the arc-shaped opening / closing portion 43 is moved from the opening position shown in FIG. By returning to the closed position shown in FIG. 3, the hot water can be stopped.

  Thus, since the opening / closing device for opening and closing the hot water outlet 15 is the rotary operation type cock 40, the operability is good. Moreover, when the tap hole 15 is closed by the arc-shaped opening / closing portion 43, it is difficult to form a gap between the arc surface 15C of the tap hole 15 and the arc-shaped opening / closing portion 43, and the molten aluminum U is easily broken. In this embodiment, a handle (not shown) is fixed to the attachment hole 41B at the front end of the trunk, and the cock body 41 is rotated by operating the handle.

  Further, since the cock body 41 has a hollow cross-sectional shape, the following effects can be obtained. If the cross-sectional shape is a hollow shape, the heat capacity of the cock body 41 is smaller than the solid shape, and the temperature of the molten aluminum U is unlikely to decrease. Therefore, it is possible to prevent re-solidification of the molten aluminum U, and no hot water discharge is caused.

  In the present embodiment, as shown in FIG. 6, three cycles of charging the aluminum metal block U into the crucible 20, irradiating the input aluminum metal block U with plasma, and discharging the molten aluminum U melted by plasma irradiation are performed in one cycle (an example). About 30 seconds), and this is executed in accordance with the production cycle of the die casting machine. And the weight of the aluminum metal lump U put into the crucible 20 is an amount (specifically, about 1 kg to 3 kg) used for one molding of the die casting machine. That is, in the present embodiment, the required amount of aluminum metal is melted, and after melting, the aluminum metal is supplied to the die casting machine and is all used for forming. Therefore, the holding furnace provided conventionally can be abolished.

  In the present embodiment, an argon plasma melting apparatus 50 using argon as the working gas is used. Since argon plasma does not contain oxygen, oxidation of dissolved aluminum can be suppressed. In addition, since argon plasma is easy to stabilize and turbulent flow is unlikely to occur, entanglement of oxide in the molten aluminum U is suppressed.

  In this embodiment, a tungsten electrode is used as an electrode for generating a plasma arc. When the electrode is made of carbon or copper, part of the electrode may be melted and mixed into the molten aluminum U. However, if it is a tungsten electrode, the melting point is high and it is difficult to melt, so there is little or no fear of mixing.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.
The molten aluminum supply device S of the second embodiment is obtained by changing the structure of the cock with respect to the molten aluminum supply device S of the first embodiment, and the other configuration is the same as that of the first embodiment. Therefore, here, the description will focus on the differences, and the description of other parts will be omitted.

  In the first embodiment, the cock body 41 has a hollow shape. In the second embodiment, as shown in FIGS. 7 and 8, the shape of the cock body 141 is a solid shape. The cock body 141 has a configuration in which a solid semicircular arc-shaped opening / closing portion 143 is provided at the tip of a solid cylindrical body 142. As with the cock body 41, the cock body 141 opens and closes the hot water outlet hole 15 by a rotating operation.

  However, when the cock main body 141 has a solid shape, the heat capacity of the cock main body 141 becomes larger than that of the hollow shape, and the temperature of the molten aluminum U tends to decrease. Therefore, there is a concern about clogging of the hot water discharge pipe 30 due to re-solidification of the molten aluminum U.

  In order to prevent such clogging of the hot water discharge pipe 30, in the second embodiment, as shown in FIG. 9, the plasma arc is irradiated twice, that is, when the aluminum metal lump U is melted and when the hot water is discharged. If the plasma arc is re-irradiated when the hot water is discharged, the re-solidified molten aluminum U can be remelted, so that the hot water pipe 30 can be prevented from clogging.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In the first and second embodiments, aluminum is exemplified as an example of the metal to be dissolved. However, the application target of the present invention is not limited to aluminum, and can be applied to copper, iron, magnesium, and zinc. It is.

  (2) In the first and second embodiments, the rotary operation type cock 40 is illustrated as an example of the opening / closing device that opens and closes the tap hole 15, but the opening / closing device is not limited to the cock 40. For example, the hot water outlet 15 may be opened and closed by sliding an open / close plate.

  (3) In the first and second embodiments, the lowering method is shown as a molten aluminum pouring structure. Specifically, a structure in which molten aluminum is discharged from the bottom wall 22 of the crucible 20 is shown. The bottom removal method may be any structure as long as it has a structure in which a molten metal is drawn out by forming a molten metal portion in the lower part of the crucible 20 that is a container. For example, a molten metal hole is formed in the lower part of the side wall of the crucible 20 You may take a bath. In short, any structure may be used as long as the hot water is discharged from at least the lower side than the surface F of the molten aluminum.

  (4) In Embodiments 1 and 2, argon is used as the working gas for generating plasma. However, the working gas is not limited to argon, and for example, an inert gas such as helium can be used. . However, air cannot be used because the dissolved metal oxidizes.

10 ... stand 15 ... tapping hole (corresponding to "tapping section" of the present invention)
20 ... crucible (corresponding to "container" of the present invention)
DESCRIPTION OF SYMBOLS 30 ... Hot water pipe 40 ... Cock 41 ... Cock main body 43 ... Arc-shaped opening / closing part 50 ... Argon plasma melting apparatus 51 ... Plasma torch 80 ... Injection sleeve S ... Aluminum molten metal supply apparatus (equivalent to the "supply apparatus" of this invention)

Claims (8)

A supply device for supplying molten metal to a die casting machine,
A container,
A supply apparatus comprising: a plasma melting apparatus that irradiates a metal lump placed in the container with a plasma arc and melts the molten metal in a molten metal. A tapping part that is formed in the lower part of the container and pours out the molten metal;
The supply device according to claim 1, further comprising an opening / closing device that opens and closes the hot water supply section.   The supply device according to claim 1, wherein the opening / closing device is a rotary operation type cock having a cylindrical cock body.   The supply device according to claim 3, wherein the cock body has a hollow cross-sectional shape.   The supply apparatus according to any one of claims 1 to 4, wherein the plasma melting apparatus is an argon plasma melting apparatus using argon as a working gas.   6. The supply apparatus according to claim 1, wherein the plasma melting apparatus has a tungsten electrode as an electrode for generating the plasma arc.   A method for supplying a molten metal, comprising: irradiating a metal lump with a plasma arc from a plasma melting apparatus to melt the metal lump in a molten metal and supplying the molten metal to a die casting machine.   The method of supplying molten metal according to claim 7, wherein the plasma arc is irradiated twice with respect to the metal in the container at the time of melting the metal lump and at the time of discharging the molten metal.

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