JP5432812B2 - Non-ferrous metal melting furnace and non-ferrous metal melting method - Google Patents

Description

  The present invention relates to a non-ferrous metal melting furnace for melting a non-ferrous metal such as an aluminum alloy to be used for manufacturing various cast products.

  Conventionally, various cast products have been manufactured by once melting non-ferrous metals such as aluminum alloys, and melting for non-ferrous metals by heating the molten metal with a radiant flame from a burner using fossil fuel such as petroleum. A furnace is disclosed (for example, Patent Document 1).

Japanese Patent No. 3871646

  As shown in FIGS. 7 and 8, the melting furnace for nonferrous metals according to the invention described in Patent Document 1 heats the molten metal in the melting chamber 11 by the flame radiation of the burner 12 and puts it into the molten metal. Dissolve. Further, the molten metal is circulated in the non-ferrous metal melting furnace 10 by a circulation device 13 such as a pump, thereby facilitating melting of the non-ferrous metal and shortening the melting time.

However, the non-ferrous metal melting furnace 10 using the burner 12 has a problem of poor thermal efficiency because it is indirect heating via air having a low thermal conductivity or radiation.
For this reason, it is conceivable to heat the molten metal at a higher temperature. However, raising the temperature makes it easier for oxides to be generated in the molten metal, resulting in a new problem that the quality deteriorates.
Even if the non-ferrous metal is not heated at a high temperature, the surface of the non-ferrous metal is often already covered with an oxide containing a large amount of air. As a result, since the nonferrous metal is difficult to dissolve, there is a problem that the nonferrous metal must be mechanically pushed into the molten metal.

As one of the improvement measures, there is a nonferrous metal melting furnace using an electric heater, and the present applicant has already filed a patent application (Japanese Patent Application No. 2008-266892).
In this non-ferrous metal melting furnace, as shown in FIGS. 9 and 10, the electric heater 22 placed in the dip tube is immersed in the molten metal in the heating chamber 21, and the molten metal is heated by the electric heater 22 without air. To do. That is, since the heat generated in the electric heater 22 can be efficiently transmitted to the molten metal, the temperature of the electric heater 22 is not increased more than necessary, and oxides are not easily generated.
Accordingly, the non-ferrous metal melting furnace 20 is suitable for melting a fine non-ferrous metal that has a large surface area relative to its volume and is likely to generate an oxide.

  Further, by supplying the molten metal to the funnel-shaped spiral part 24 with the pump 23, when the molten metal flows from the top to the bottom of the spiral part 24, a vortex is generated in the spiral part 24, and the molten metal is melted in the non-ferrous metal melting furnace. It is circulated within 20. Since the introduced nonferrous metal is quickly dispersed in the molten metal by the vortex in the spiral portion 24, it is not necessary to mechanically push the nonferrous metal into the molten metal in order to easily dissolve the nonferrous metal.

However, both of the conventional non-ferrous metal melting furnaces 10 and 20 require large circulation devices 13 and 23 for circulating the molten metal in the non-ferrous metal melting furnaces 10 and 20. There is a problem that 23 takes up space.
In addition, in order to sink nonferrous metal into the molten metal, a device that mechanically pushes the nonferrous metal into the molten metal and a spiral portion 24 are required, and they take up space as well as the circulation devices 13 and 23 and air is contained in the molten metal. Will be involved.

  Accordingly, an object of the present invention is to provide a non-ferrous metal melting furnace and a non-ferrous metal melting method in which an apparatus for circulating molten metal does not take up space, and an apparatus for sinking charged non-ferrous metal also does not take up space. Is to provide.

In order to achieve the above object, a melting furnace (30) for a nonferrous metal according to claim 1 of the present invention includes a melting chamber (31) for heating a molten metal, and circulates the molten metal inside and throws it into the molten metal. A non-ferrous metal melting furnace (30) for melting a non-ferrous metal, which is immersed in the molten metal in the melting chamber (31), and at least a pair facing each other at a predetermined interval in the horizontal direction to generate heat into the molten metal. An electrode (33) for applying heat and at least one of the upper part and the lower part of the melting chamber (31) are arranged to generate a magnetic field that intersects the current flowing between the pair of electrodes (33) substantially perpendicularly. includes a magnet (34), and Rutotomoni give a thrust to the molten metal, which is connected to a pair of electrodes (33), the current flowing between the pair of electrodes (33), the non-ferrous metal is minutely vibrating the molten metal Adhering air to non-ferrous gold Be provided with a larger heat transfer coefficient of the non-ferrous metal surfaces to liberate rectifier for pulsating capable of easily sink nonferrous metals (35) from which it said.

In addition, the nonferrous metal melting method according to claim 2 includes a melting chamber (31) for heating the molten metal, and circulates the molten metal inside and injects the nonferrous metal into the molten metal (30). A method for melting a non-ferrous metal, wherein the pair of electrodes (33) is immersed in a molten metal in the melting chamber (31), and a current is passed between at least a pair of electrodes (33) facing each other with a predetermined interval left and right. ) Is heated to heat the non-ferrous metal in the molten metal, and the magnet (34) disposed above or below the melting chamber (31) is used for the pair of electrodes (33). ) produce a magnetic field substantially perpendicular to the current flowing between, by circulating the molten metal by the action in the longitudinal direction electromagnetic force according to Fleming's left-hand rule to melt locations where the current and the magnetic field intersect, further Using the current flowing between the pair of electrodes (33) as a pulsating flow, the gas adhering to the non-ferrous metal is liberated from the non-ferrous metal by microvibrating the molten metal, increasing the heat transfer coefficient of the non-ferrous metal surface and non-ferrous It is characterized by facilitating the sinking of metal .

  Here, the symbols in the parentheses indicate corresponding elements or corresponding matters described in the drawings and the embodiments for carrying out the invention described later.

According to the melting furnace for a nonferrous metal according to claim 1 of the present invention, at least a pair of electrodes immersed in the molten metal in the melting chamber and facing each other at a predetermined interval in the horizontal direction, and above or below the melting chamber And a magnet that generates a magnetic field that intersects the current flowing between the pair of electrodes substantially perpendicularly, so that electromagnetic force according to Fleming's left-hand rule is generated at a location where the current and the magnetic field intersect. Occurs and thrust is given to the molten metal.
And a pair of electrodes generate | occur | produce itself with the electric current which flows between them, and give heat to a molten metal.
In other words, the device for circulating the molten metal is an electrode that also exists in the melting chamber and also serves as a heat source, and a magnet that is disposed above or below the melting chamber, and therefore does not take up space. Therefore, even if a separate circulation device is required, the thrust is applied to the molten metal by the electrodes and the magnets, so that a smaller circulation device than the conventional one is sufficient and does not take up space.
Furthermore, if the current flowing between the electrodes is large and the magnetic flux density of the magnet is high, the generated electromagnetic force increases, and the molten metal can be circulated only by the electromagnetic force, so there is no need for a circulation device other than the electrodes and magnets, Saves space.

In addition, since the rectifier is connected to the pair of electrodes and pulsating the current flowing between the pair of electrodes, the molten metal can be microvibrated by flowing the current. Thereby, since the air adhering to the nonferrous metal can be liberated from the nonferrous metal, precipitation of the nonferrous metal is promoted. Further, even when the nonferrous metals are entangled with each other and difficult to sink, the entanglement can be solved by minute vibrations, so that the nonferrous metal can easily sink. Therefore, the nonferrous metal can be efficiently dissolved, so that the dissolution rate is increased.
Even if the non-ferrous metal sinks, air may remain on the surface of the non-ferrous metal in the molten metal, but the residual air can be released from the non-ferrous metal by the minute vibration of the molten metal. Almost no air with low thermal conductivity remains, and as a result, the heat transfer coefficient of the non-ferrous metal surface can be increased.
Furthermore, since the air melted into the molten metal by minute vibrations can be removed from the molten metal, the thermal conductivity of the molten metal can be increased.
Here, since the rectifier is smaller than the device conventionally used for sinking nonferrous metal into the molten metal (for example, a spiral part), and the electrode serves as a heat source and a circulation device, the nonferrous metal charged into the molten metal is submerged. The rectifiers and electrodes that are the devices of this do not take up space.

Further, according to the method for melting a non-ferrous metal according to claim 2 , the pair of electrodes is heated by flowing current between at least a pair of electrodes which are immersed in the molten metal in the melting chamber and spaced apart from each other at a predetermined interval. The molten metal is heated to heat the non-ferrous metal in the molten metal, and a magnetic field is generated substantially perpendicularly to the current flowing between the pair of electrodes by a magnet disposed above or below the melting chamber. Since the electromagnetic force according to Fleming's left-hand rule acts in the front-rear direction on the melt where the current and the magnetic field intersect, the nonferrous metal can be circulated without taking up space. That is, the molten metal is heated by the electrode, and further, the molten metal is circulated by the electrode and the magnet, so that space is saved.

In addition, the current flowing between the pair of electrodes is used as a pulsating flow, and the gas adhering to the non-ferrous metal is liberated from the non-ferrous metal by microvibrating the molten metal, increasing the heat transfer coefficient on the surface of the non-ferrous metal and Because it is easy to sink, non-ferrous metals can be submerged in the molten metal without taking up space. That is, the electrode, which is a device for sinking the nonferrous metal charged into the molten metal, serves as both a heat source and a circulation device, and therefore does not take up space for sinking the nonferrous metal into the molten metal.

Here, the non-ferrous metal means a solid non-ferrous metal, and the molten metal means a non-ferrous metal dissolved.
Here, although the circulation device is described in Patent Document 1 described above, it is not described at all that the circulation device is a pair of electrodes and a magnet, like the melting furnace for non-ferrous metals of the present invention, It does not describe a method for dissolving non-ferrous metals in which electromagnetic force is applied according to Fleming's left-hand rule.

It is a top view which shows the melting furnace for nonferrous metals which concerns on embodiment of this invention. It is the BB sectional drawing of FIG. 1 which shows the melting furnace for nonferrous metals which concerns on embodiment of this invention. It is a principal part expanded sectional view which shows the melting furnace for nonferrous metals which concerns on embodiment of this invention. It is a principal part expanded sectional view which shows the melting furnace for nonferrous metals which concerns on other embodiment of this invention. It is a principal part expanded sectional view which shows the melting furnace for nonferrous metals which concerns on other embodiment of this invention. It is a principal part expanded sectional view which shows the melting furnace for nonferrous metals which concerns on other embodiment of this invention. It is a top view which shows the melting furnace for nonferrous metals which concerns on a prior art example. It is a front view of the melting furnace for nonferrous metals shown in FIG. It is a top view which shows the melting furnace for nonferrous metals which concerns on another prior art example. It is the sectional view on the AA line of FIG. 9 which shows the nonferrous metal melting furnace which concerns on another prior art example.

With reference to FIG. 1 thru | or FIG. 3, the melting furnace 30 for nonferrous metals and the melting method of a nonferrous metal which concern on embodiment of this invention are demonstrated.
The non-ferrous metal melting furnace 30 according to this embodiment melts a non-ferrous metal such as an aluminum alloy in order to produce a cast product such as die casting.
The non-ferrous metal melting furnace 30 includes a melting chamber 31 and a holding chamber 32 as a chamber for storing molten metal, and the melting chamber 31 mainly includes an electrode 33, a magnet 34, and a rectifier 35.

The melting chamber 31 is a chamber for heating the molten metal, and non-ferrous metal (ingot or chips) charged into the molten metal is melted by the heat of the molten metal.
A column body 31 a that is exposed above the surface of the molten metal from the hearth 30 a is erected at a substantially central portion of the melting chamber 31, and serves as a flow path 31 b that goes around the melting chamber 31.

  The holding chamber 32 is adjacent to the melting chamber 31 and is separated by a weir 38. Then, the molten metal exceeding the capacity of the melting chamber 31 is filtered by the filter 39, overflows the weir 38 and is supplied to the holding chamber 32.

The electrodes 33 are immersed in the molten metal in the melting chamber 31 so as to be opposed to each other at least a pair (here, two pairs) in the horizontal direction at predetermined intervals. Specifically, as shown in FIGS. 1 and 2, one pair of electrodes 33a and 33b are disposed at both ends in the width direction of a predetermined position of the flow path 31b. The other pair of electrodes 33c and 33d are arranged at both ends in the width direction of the flow path 31b at positions opposite to the one electrodes 33a and 33b with respect to the column body 31a. Here, in each case, the electrodes 33b and 33c on the inner peripheral side (column body 31a side) were positive electrodes, and the electrodes 33a and 33d on the outer peripheral side were negative electrodes.
The electrode 33 is made of carbon or a carbon compound having a higher specific resistance than a metal such as copper.

Further, with the lower end of the electrode 33 exposed, the surface from the lower portion of the electrode 33 to the portion exposed on the surface of the molten metal is covered with a protective material 36 that prevents erosion from the molten metal. The protective material 36 is made of silicon nitride or the like, and silicon nitride has higher specific resistance and thermal conductivity than carbon or a carbon compound that is the material of the electrode 33.
Further, the lower end of the electrode 33 not covered with the protective material 36 was formed to be narrower than the portion covered with the protective material 36.
Then, the electrode 33 generates heat by the current flowing between the electrodes 33, and becomes a heat source for applying heat to the molten metal.
The molten metal temperature in the melting chamber 31 is monitored with a thermocouple (not shown) and a temperature controller (not shown), and the amount of current flowing between the electrodes 33 (that is, the amount of generated heat) is controlled according to the molten metal temperature. The temperature is set to a desired temperature.
In addition, a ground electrode 40 is also immersed in the molten metal and is grounded.

The magnet 34 is mounted and disposed on the lid 30 b above the electrodes 33 so as to generate a magnetic field that intersects substantially perpendicularly to the current flowing between the electrodes 33. Here, since there are two pairs of electrodes 33, two magnets 34 are arranged so that a magnetic field acts between the electrodes 33.
Further, any magnet 34 has an N pole on the upper side and an S pole on the lower side. Therefore, the direction of the magnetic field between the electrodes 33 is from bottom to top.
The magnet 34 may be a permanent magnet or an electromagnet.

The rectifier 35 is connected to each electrode 33 via the switching control unit 41, and the current flowing between the pair of electrodes 33 is a pulsating current. The current that is pulsating in the rectifier 35 is controlled to a frequency of 0.5 to 100 Hz by the switching control unit 41, and the waveform, amplitude, and the like are also controlled. A current controlled in this way flows between the electrodes 33.
An insulating transformer 42 is attached to the power supply side of the rectifier 35 to prevent electric shock.
Such a rectifier 35 is generally widespread, and is smaller than the spiral portion 24 that has been conventionally used for sinking non-ferrous metal in molten metal.

In the non-ferrous metal melting furnace 30 configured as described above, the electrode 33 generates heat by flowing a current, and the molten metal is heated.
Then, a magnetic field is generated substantially perpendicularly to the current flowing between the electrodes 33, and an electromagnetic force according to Fleming's left-hand rule is applied in the front-rear direction to the melt where the current and the magnetic field intersect, so that the melt is melted in the melting chamber. It circulates in 31.
That is, on one side of the pair of electrodes 33a and 33b, as shown in FIG. 3, the current flows from right to left and the direction of the magnetic field is from bottom to top. Works from the front of the page. On the other pair of electrodes 33c and 33d side, the current is from left to right and the magnetic field is from bottom to top, so that electromagnetic force acts from the back to the front of the page.
Therefore, the molten metal flow in the entire melting chamber 31 is clockwise as shown in FIG.

  Moreover, when the current which is a pulsating current flows, the molten metal vibrates slightly, and the gas adhering to the nonferrous metal is released from the nonferrous metal. As a result, the heat transfer coefficient of the non-ferrous metal surface increases and the non-ferrous metal sinks into the molten metal.

  According to the non-ferrous metal melting furnace 30 configured as described above, since the molten metal can be circulated by the electrode 33 and the magnet 34, the conventional large-scale circulation devices 13 and 23 are unnecessary. Since the electrode 33 and the magnet 34 are smaller than the conventional circulation devices 13 and 23, the electrode 33 also serves as a heat source, and the magnet 34 is attached to the lid 30 b of the non-ferrous metal melting furnace 30. Even if the molten metal is circulated, the electrode 33 and the magnet 34 do not take up space.

Moreover, since the molten metal is vibrated minutely, the air adhering to the nonferrous metal can be released from the nonferrous metal, and precipitation of the nonferrous metal is promoted. Further, even when the nonferrous metals are entangled with each other and difficult to sink, the entanglement can be solved by minute vibrations, so that the nonferrous metal can easily sink. Therefore, the nonferrous metal can be efficiently dissolved, so that the dissolution rate is increased.
In addition, even if the nonferrous metal is submerged in the molten metal by vortexing or the like as before, air may remain on the surface of the nonferrous metal in the molten metal. Since it can be liberated from the metal, almost no air with low thermal conductivity remains on the non-ferrous metal surface, and as a result, the heat transfer coefficient of the non-ferrous metal surface can be increased. Therefore, the efficiency of dissolution increases.
Furthermore, since the air melted into the molten metal by minute vibrations can be removed from the molten metal, the thermal conductivity of the molten metal can be increased.
Here, since the rectifier 35 is smaller than the spiral part 24 or the like conventionally used for sinking nonferrous metal into the molten metal, and the electrode 33 serves as a heat source and a circulation device, the nonferrous metal charged into the molten metal is submerged. The rectifier 35 and the electrode 33, which are the devices of FIG.

In addition, since the electrode 33 is directly immersed in the molten metal without putting the electrode 33 in a conventional dip tube or the like, the molten metal can be heated without passing through air or other solid having a low thermal conductivity, and thermal efficiency. Is good. In addition, although the electrode 33 is covered with the protective material 36, since the heat conductivity of the protective material 36 is larger than the heat conductivity of the electrode 33, the heat loss by the protective material 36 is smaller than the heat loss by the conventional dip tube. .
Moreover, since the lower end of the electrode 33 is exposed, a current flows mainly between the lower ends of the electrodes 33, and the current density between the electrodes 33 is increased. Therefore, since the electromagnetic force per unit area becomes large, the efficiency of molten metal circulation is good.

Moreover, since the surface from the lower part of the electrode 33 to the part exposed on the surface of the molten metal is covered with the protective material 36, most of the electrode 33 can be protected from erosion by the molten metal.
Further, since the lower end of the electrode 33 is formed thin, the current density at the lower end of the electrode 33 is increased, and the amount of heat generated in this portion is increased. That is, since the amount of heat generated in the portion directly touching the molten metal is increased, the thermal efficiency is better.

  Further, a column body 31a that is exposed above the surface of the molten metal from the hearth 30a is provided at a substantially central portion of the melting chamber 31 to form a flow path 31b that goes around the melting chamber 31, and the width of the flow path 31b. Since the pair of electrodes 33 are arranged at both ends in the direction, a large flow along the flow path 31b can be created. Therefore, since the portion where the molten metal stagnates in the melting chamber 31 is difficult to occur, the quality of the molten metal becomes uniform.

  Moreover, since the molten metal is supplied to the holding chamber 32 by overflowing the weir 38, the height of the molten metal surface in the melting chamber 31 can be kept substantially constant. As a result, the heat generating portion of the electrode 33 is always immersed in the molten metal, so that the heat of the electrode 33 can be given to the molten metal as much as possible, and the amount of the molten metal stored in the holding chamber 32 is minimized. Can be.

Although the magnet 34 is attached to the lid 30b of the nonferrous metal melting furnace 30, the present invention is not limited to this, and it may be disposed below the melting chamber 31 as shown in FIG. At this time, the stainless steel plate 43 is sandwiched between the hearth 30 a and the magnet 34.
Further, the magnet 34 may be disposed above and below the melting chamber 31. At this time, it is necessary to arrange the upper and lower magnets 34 so that the direction of the magnetic field between the electrodes 33 is one direction.

Further, although the current is pulsated by the rectifier 35, the means for pulsating the current is not limited to this. Furthermore, the current need not be a pulsating flow, and even in this case, the molten metal can be circulated in the melting chamber 31.
Moreover, although the surface of the electrode 33 was covered with the protective material 36, the protective material 36 is not required if the electrode 33 is excellent in anti-erosion property.

  Furthermore, although the lower end of the electrode 33 is formed thinly, the present invention is not limited to this, and the lower end of the electrode 33 may have the same thickness as the portion covered with the protective material 36 as shown in FIG.

Further, although the magnet 34 is fixed to the lid of the melting chamber 31, as shown in FIG. 6, on the furnace floor 30a side, for example, a position adjusting mechanism 44 that makes it possible to adjust the up and down position of the magnet 34 that has been turned up by the cylinder 44a. May be provided.
Here, if the magnet 34 is lowered to move the magnet 34 away from the current flowing between the electrodes 33, the magnetic flux density of the portion acting on the current is reduced, so that the electromagnetic force serving as a thrust is reduced and the circulating speed of the molten metal is reduced. . On the other hand, when the magnet 34 is raised to bring the magnet 34 close to the current flowing between the electrodes 33, the magnetic flux density of the portion acting on the current increases, so that the electromagnetic force that becomes a thrust increases and the circulation speed of the molten metal increases. If the position adjusting mechanism 44 is provided as described above, the molten metal circulation speed can be controlled independently of the molten metal temperature control.
Further, even when the magnet 34 is disposed above the melting chamber 31, the position adjusting mechanism 44 may be provided.

Further, only the electrode 33 and the magnet 34 are used as the circulation device. However, if the generated electromagnetic force is insufficient as a thrust for circulating the molten metal, a separate circulation device conventionally used such as a pump is supplementarily used. It may be used. In this case, a small pump or the like is sufficient and does not take up space.
Further, the column body 31 a is erected in the melting chamber 31, but the invention is not limited to this, and the molten metal may be circulated in the melting chamber 31.

Further, the nonferrous metal melting furnace 30 is provided with the melting chamber 31 and the holding chamber 32. However, as long as there is the melting chamber 31 for heating the molten metal, there may be any number of chambers for other purposes.
Further, the direction of the current and the direction of the magnet 34 are not limited to this, and the molten metal may be circulated smoothly.

DESCRIPTION OF SYMBOLS 10 Nonferrous metal melting furnace 11 Melting chamber 12 Burner 13 Circulation apparatus 20 Nonferrous metal melting furnace 21 Heating chamber 22 Electric heater 23 Pump (circulation apparatus)
24 vortex part 30 non-ferrous metal melting furnace 30a hearth 30b lid 31 melting chamber 31a column body 31b flow path 32 holding chamber 33 electrode 33a electrode 33b electrode 33c electrode 33d electrode 34 magnet 35 rectifier 36 protective material 37 position adjusting mechanism 38 weir 39 Filter 40 Ground electrode 41 Switching control unit 42 Insulation transformer 43 Stainless steel plate 44 Position adjustment mechanism 44a Cylinder

Claims (2)

A melting furnace for heating non-ferrous metals, comprising a melting chamber for heating molten metal, circulating the molten metal inside and melting non-ferrous metals charged into the molten metal,
At least a pair of electrodes that are immersed in the molten metal in the melting chamber and face each other at a predetermined interval in the horizontal direction, and generate heat to heat the molten metal ;
A magnet that is disposed on at least one of the upper and lower sides of the melting chamber and generates a magnetic field that intersects substantially perpendicularly to the current flowing between the pair of electrodes,
Rutotomoni give a thrust to the molten metal,
Further, the current flowing between the pair of electrodes and flowing between the pair of electrodes causes the molten metal to vibrate slightly to release the air adhering to the non-ferrous metal from the non-ferrous metal and increase the heat transfer coefficient of the non-ferrous metal surface. A melting furnace for non-ferrous metals, comprising a rectifier having a pulsating flow that can easily sink . A melting method for non-ferrous metals in a melting furnace for non-ferrous metals, comprising a melting chamber for heating molten metal, circulating the molten metal inside and adding non-ferrous metals to the molten metal,
In the melting chamber, a current is passed between at least a pair of electrodes facing each other at a predetermined interval on the left and right sides to generate heat by heating the pair of electrodes to heat the non-ferrous metal in the melt. With
A magnet arranged at least one of the upper and lower sides of the melting chamber generates a magnetic field substantially perpendicular to the current flowing between the pair of electrodes, and the flaming is applied to the molten metal at the location where the current and the magnetic field intersect. The molten metal is circulated by applying the electromagnetic force according to the left hand rule in the front-rear direction .
Further, the current flowing between the pair of electrodes is pulsated, and the gas adhering to the non-ferrous metal is liberated from the non-ferrous metal by microvibrating the molten metal, increasing the heat transfer coefficient of the non-ferrous metal surface and reducing the non-ferrous metal. A method for dissolving a non-ferrous metal, characterized by being easily sunk .

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