Circulating non-ferrous metal melting furnace and non-ferrous metal melting method

Abstract

To effectively melt and increase a temperature of a nonferrous metallic material while preventing an excessive load from being applied to each electric heater and a circulation pump.SOLUTION: First, second and third electric heaters 30, 40, 60 are provided in a first temperature rise chamber 12, a second temperature rise chamber 13 and a molten metal delivery chamber 14, respectively. While a control temperature of the first temperature rise chamber 12 is set lower than that of the molten metal delivery chamber 14, a nonferrous metallic material is input from an input port 11 to obtain molten metal of which temperature has been raised to a predetermined first temperature in the first temperature rise chamber 12. Part of the molten metal of which temperature has been raised to the first temperature is received in the molten metal delivery chamber 14. The remainder of the molten metal is received in the second temperature rise chamber 13, and after the temperature of the molten metal is raised to a second temperature exceeding the first temperature by the second electric heater 40, the molten metal is circulated to the first temperature rise chamber 12. Heat of the molten metal circulated to the first temperature rise chamber 12 is applied to the nonferrous metallic material to be additionally input from the input port 11.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a circulating non-ferrous metal melting furnace and a non-ferrous metal melting method for melting non-ferrous metals such as aluminum alloys while circulating them for use in the production of various cast products such as die casting.

Background Art

[0002] Conventionally, for melting non-ferrous metals such as aluminum alloys, melting furnaces using radiant flames from gas burners using fossil fuels such as petroleum have been mainly adopted. However, since the radiant flames from gas burners using fossil fuels have problems in terms of thermal efficiency and the environment, improvement measures have been demanded.

[0003] As an improvement measure, a non-ferrous metal melting furnace having a structure in which an electric heater is immersed in molten metal is disclosed (see, for example, Patent Document 1). As shown in FIG. 3, the non-ferrous metal melting furnace 50 described in this Patent Document 1 is provided with a plurality of chambers including a melting chamber 51, a heating chamber 52, and a dross removal chamber 53. The non-ferrous metal material charged into the melting chamber 50 is melted by an electric heater 56 provided in the heating chamber 52 and heated to a predetermined temperature, and then supplied from there to a tapping chamber 55 through a calming chamber 54. The molten metal circulates from the dross removal chamber 53 to the heating chamber 52, but no electric heater is provided in this dross removal chamber 53.

[0004] Since this non-ferrous metal melting furnace 50 uses an electric heater to melt and heat the non-ferrous metal material, it has a great advantage of being superior in terms of thermal efficiency and the environment compared to the conventional melting furnace using a gas burner.

[0005] However, the present inventors did not satisfy with such a situation and further advanced research and development, and have developed a circulating non-ferrous metal melting furnace capable of melting and heating non-ferrous metal materials more efficiently with a novel configuration that has not existed so far (Patent Document 2).

[0006] As shown in Figure 4, this circulating non-ferrous metal melting furnace 101 has a furnace body 110 that includes an inlet 111 for non-ferrous metal materials, a first heating chamber 112 communicating with the inlet 111, a second heating chamber 113 arranged parallel to the first heating chamber 112 via an intermediate wall 115 and forming a circulation path for the molten metal to circulate between the first heating chamber 112 and the second heating chamber 113, and a tapping chamber 114 that communicates with the downstream side of the first heating chamber 112 and can receive a portion of the molten metal heated to a predetermined temperature in the first heating chamber 112 and from which the molten metal can be removed. The system includes a circulation pump 120 for circulating the molten metal, a plurality of first electric heaters 130 installed in the first heating chamber 112 to raise the molten metal to a predetermined first temperature, and a plurality of second electric heaters 140 installed in the second heating chamber 113 to raise the molten metal, which has been heated to the first temperature in the first heating chamber 112, to a second temperature exceeding the first temperature. The molten metal, which has been heated to the second temperature in the second heating chamber 113, is circulated back to the first heating chamber 112, and its heat is transferred to the non-ferrous metal material introduced from the inlet 111. A partition wall 117 is provided between the first heating chamber 112 and the molten metal outlet chamber 114. A connecting passage 117a is formed in this partition wall 117, connecting the first heating chamber 112 to the molten metal outlet chamber 114. The molten metal outlet chamber 114 is equipped with a mechanism (not shown) for removing the received molten metal to the outside.

[0007] According to this, molten metal is circulated by a circulation pump 120 through a circulation path formed by the first heating chamber 112 and the second heating chamber 113. A portion of the molten metal, which has been heated to a predetermined temperature (first temperature) in the first heating chamber 112 by the first electric heater 130, is received in the tapping chamber 114. Furthermore, the molten metal from the first heating chamber 112 is heated to a temperature exceeding the predetermined temperature (second temperature) in the second heating chamber 113 by the second electric heater 140, and then circulated back to the first heating chamber 112. This allows non-ferrous metal material introduced into the first heating chamber 112 from the input port 111 to be effectively melted and heated. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2010-96401 [Patent Document 2] Patent No. 6997738 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, since the circulating non-ferrous metal melting furnace 101 shown in Figure 4 does not actively control the temperature in the outlet chamber 114, the inventors came to the conclusion that if the temperature information in the outlet chamber 114 could be effectively utilized, non-ferrous metal materials could be melted and heated more efficiently.

[0010] Therefore, the object of the present invention is to provide a circulating non-ferrous metal melting furnace and a non-ferrous metal melting method that can efficiently melt and heat non-ferrous metal materials. [Means for solving the problem]

[0011] To achieve the above objective, the circulating non-ferrous metal melting furnace of the present invention is a circulating non-ferrous metal melting furnace (1) that melts non-ferrous metal materials using an electric heater, A furnace body (10) having an inlet (11) for non-ferrous metal material, a first heating chamber (12) communicating with the inlet (11), a second heating chamber (13) arranged parallel to the first heating chamber (12) via an intermediate wall (15) and forming a circulation path for molten metal to circulate with the first heating chamber (12), and a tapping chamber (14) between the first heating chamber (12) and the second heating chamber (13) and communicating with the downstream side of the first heating chamber (12) or the upstream side of the second heating chamber (13) to receive a portion of the molten metal heated to a predetermined temperature in the first heating chamber (12) and to allow the molten metal to be removed, A circulation pump (20) is provided in the first heating chamber (12) or the second heating chamber (13) or both, for circulating the molten metal. The first heating chamber (12) is provided with a plurality of first electric heaters (30) that raise the temperature of the molten metal to a predetermined first temperature, Multiple second electric heaters (40) are provided in the second heating chamber (13) and raise the molten metal, which has been heated to a first temperature in the first heating chamber (12), to a second temperature that exceeds the first temperature. Multiple third electric heaters (60) are provided in the aforementioned hot water outlet chamber (14), The system includes a control unit (100) capable of controlling the output of the first electric heater (30), the second electric heater (40), and the third electric heater (60), respectively. The control unit (100) controls the output of the first electric heater (30), the second electric heater (40), and the third electric heater (60) respectively so that the control temperature of the first heating chamber (12) is lower than the control temperature of the hot water outlet chamber (14), and circulates the molten metal heated to the second temperature in the second heating chamber (13) to the first heating chamber (12) to transfer its heat to the non-ferrous metal material introduced from the inlet (11).

[0012] Furthermore, the circulating non-ferrous metal melting furnace (1) of the present invention is characterized in that the non-ferrous metal material is aluminum or an aluminum alloy.

[0013] The present invention provides a non-ferrous metal melting method in which a first heating chamber (12) equipped with a plurality of first electric heaters (30) and a second heating chamber (13) equipped with a plurality of second electric heaters (40) are arranged side by side with an intermediate wall (15) in between to form a molten metal circulation path, an inlet (11) for non-ferrous metal material is provided on one end of the intermediate wall (15) between the first heating chamber (12) and the second heating chamber (13), and a molten metal is provided on the other end of the intermediate wall (15) between the first heating chamber (12) and the second heating chamber (13). A method for melting a non-ferrous metal material using a circulating non-ferrous metal melting furnace (1) which is configured to have a gap passage (17a) that communicates with a removable outlet chamber (14) equipped with multiple third electric heaters (60), and to perform temperature control in each of the first heating chamber (12), the second heating chamber (13), and the outlet chamber (14), and to circulate the molten metal via a circulation pump (20) provided in the first heating chamber (12) or the second heating chamber (13) or both, With the control temperature of the first heating chamber (12) set lower than the control temperature of the hot water outlet chamber (14), The non-ferrous metal material is introduced through the inlet (11) and heated to a predetermined first temperature in the first heating chamber (12) to form molten metal. A portion of the molten metal heated to the first temperature is received in the outlet chamber (14), the remainder of the molten metal is received in the second heating chamber (13), heated to a second temperature exceeding the first temperature by the second electric heater (40), and then circulated back to the first heating chamber (12). The heat of the molten metal circulated back to the first heating chamber (12) is then transferred to the non-ferrous metal material newly introduced through the inlet (11).

[0014] Furthermore, the non-ferrous metal dissolution method of the present invention is characterized in that the non-ferrous metal material is aluminum or an aluminum alloy.

[0015] The symbols in parentheses above indicate the corresponding elements or items shown in the drawings and the embodiments for carrying out the invention described later. [Effects of the Invention]

[0016] According to the present invention, a circulating non-ferrous metal melting furnace is provided with a small volume and an unprecedentedly large melting capacity. This furnace is configured such that the control temperature of the first heating chamber is set lower than the control temperature of the outlet chamber, allowing for efficient melting and heating of non-ferrous metal materials. Furthermore, since the control temperature of the first heating chamber is set lower than the control temperature of the outlet chamber, planned temperature control can be achieved without placing an excessive load on the first electric heaters. This is based on the premise that the control temperature of the first heating chamber is set lower than the control temperature of the outlet chamber.

[0017] Then, in the circulation path formed by the first heating chamber and the second heating chamber, the molten metal is circulated by a circulation pump, and part of the molten metal heated to a predetermined temperature (first temperature) by the first electric heater in the first heating chamber is received in the tapping chamber. Also, the molten metal from the first heating chamber is heated to a temperature (second temperature) exceeding the predetermined temperature by the second electric heater in the second heating chamber and then circulated back to the first heating chamber. Therefore, the non-ferrous metal material introduced into the first heating chamber from the inlet can be efficiently melted and heated up.

[0018] That is, the molten metal heated to the second temperature (having a temperature higher than the first temperature) is used to melt the non-ferrous metal material introduced into the first heating chamber and heat it up to the first temperature. Thus, this non-ferrous metal material can be efficiently melted in a short time and heated up to the molten metal at the predetermined temperature.

[0019] It is important to set the controlled temperature of the first heating chamber lower than the controlled temperature of the tapping chamber for the following reasons. The relationship between the controlled temperature of the tapping chamber and the controlled temperature of the first heating chamber is determined by the following factors. That is, in addition to the fluctuation of the molten metal temperature entering the first heating chamber due to the variation in the input amount of the non-ferrous metal material per unit time and the change in weight per piece, even if the output of the first electric heater is controlled due to the fluctuation of the tapping amount, there will still be a remaining temperature fluctuation in the first heating chamber. However, by controlling the output of the third electric heater provided in the tapping chamber, the remaining temperature fluctuation can be reduced. However, since the electric heater has heating ability but no cooling ability, in order to improve the temperature controllability of the tapping chamber, it is necessary to constantly set the controlled temperature of the first heating chamber lower than the controlled temperature of the tapping chamber. Here, as shown in FIG. 5, the target temperature of the controlled temperature of the first heating chamber is set lower than the target temperature of the controlled temperature of the tapping chamber by the following value (the upper fluctuation range of the first heating chamber + the lower fluctuation range of the tapping chamber + the margin δ). Here, the controlled temperature of the second heating chamber only needs to be higher than the controlled temperature of the first heating chamber and can be determined independently of the controlled temperature of the tapping chamber.

[0020] In addition, according to the present invention, since the non-ferrous metal material is aluminum or an aluminum alloy, various casting products using aluminum can be manufactured well.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic plan view showing an embodiment of a circulating non-ferrous metal melting furnace according to the present invention. [Figure 2] It is a schematic plan view showing another embodiment of a circulating non-ferrous metal melting furnace according to the present invention. [Figure 3] It is a schematic plan view showing a circulating non-ferrous metal melting furnace according to a conventional example. [Figure 4] It is a schematic plan view showing a circulating non-ferrous metal melting furnace according to another conventional example. [Figure 5] It is a graph showing the relationship between the position along the flow of the molten metal and the molten metal temperature.

Embodiments for Carrying Out the Invention

[0022] Referring to the drawings, a circulating non-ferrous metal melting furnace 1 according to an embodiment of the present invention and a non-ferrous metal melting method using the circulating non-ferrous metal melting furnace 1 will be described.

[0023] As shown in FIG. 1, the circulating non-ferrous metal melting furnace 1 according to the present embodiment immerses an electric heater, except for its upper end portion, into the molten metal while circulating the molten metal and uses its heat to melt and raise the temperature of the non-ferrous metal material. It includes a furnace body 10, a circulation pump 20, a first electric heater 30, a second electric heater 40, a third electric heater 60, thermometers T1 to T11, and a control unit 100 for controlling the entire electrical system.

[0024] The furnace body 10 has a substantially rectangular plane shape formed by a furnace wall 10a, and includes an inlet 11 for non-ferrous metal materials, a first heating chamber 12, a second heating chamber 13, and a tapping chamber 14 from which the molten metal can be taken out. Note that the planar shape of the furnace body 10 is not limited to a rectangular shape.

[0025] The input port 11 is located upstream of the second heating chamber 13. The first heating chamber 12 is connected to the input port 11 and receives non-ferrous metal materials introduced from the input port 11. The second heating chamber 13 is installed alongside the first heating chamber 12 via an intermediate wall 15, forming a circulation path for the molten metal to circulate between the two chambers.

[0026] The hot water outlet chamber 14 is located on the opposite side of the inlet 11, via a guide channel 18 that is provided to communicate with the upstream side of the second heating chamber 13. The first heating chamber 12 and the second heating chamber 13 are separated from the guide channel 18 by a partition wall 17, except for a gap passage 17a that communicates with the upstream side of the second heating chamber 13. A degassing device 70 is installed in the guide channel 18, which generates an inert gas to adsorb aluminum slag and float it to the surface of the molten metal. The aluminum slag is removed manually. This molten metal outlet chamber 14 is equipped with a mechanism (not shown) for removing the received molten metal to the outside. An inlet 11 for non-ferrous metal materials is provided at one end of the intermediate wall 15 between the first heating chamber 12 and the second heating chamber 13, and a gap passage 17a communicating with the hot water outlet chamber 14 is provided at the other end of the intermediate wall 15 between the first heating chamber 12 and the second heating chamber 13.

[0027] Gap passages 16 (first gap passage 16a and second gap passage 16b) are formed between the ends of the intermediate wall 15 and the opposing furnace wall 10a and partition wall 17, respectively. Therefore, the circulation path is formed in the following order from the upstream side (inlet 11): first gap passage 16a, first heating chamber 12, second gap passage 16b, and second heating chamber 13.

[0028] The circulation pump 20 is installed downstream of the second heating chamber 13 and circulates the molten metal along the circulation path. The location and number of the circulation pumps 20 are not limited. Therefore, they can be installed in the first heating chamber 12, or they can be installed in both the first heating chamber 12 and the second heating chamber 13.

[0029] The first electric heater 30 is installed in the first heating chamber 12 and heats the molten metal to a predetermined first temperature. In this embodiment, a total of 11 first electric heaters 30 are installed, but this number is not limited. The second electric heater 40 is installed in the second heating chamber 13 and raises the molten metal, which has been heated to the first temperature in the first heating chamber 12, to a second temperature that exceeds the first temperature. In this embodiment, a total of six second electric heaters 40 are provided, but this number is not limited. The third electric heater 60 is installed in the molten metal outlet chamber 14 and raises the temperature of the molten metal in the molten metal outlet chamber 14. In this embodiment, a total of four third electric heaters 60 are installed, but this number is not limited.

[0030] Thermometers T1 to T11 are thermocouple-type sensors, installed in the first heating chamber 12, the second heating chamber 13, and the molten metal outlet chamber 14, respectively, to measure the temperature of the molten metal. The number of these sensors is not limited.

[0031] The control unit 100, although not shown in the figure, includes a CPU, ROM, RAM and other memory units, and controls the circulation pump 20, the first electric heater 30, the second electric heater 40, and the third electric heater 60, respectively, based on temperature information from thermometers T1 to T11 and information on non-ferrous metal materials.

[0032] In this embodiment, the non-ferrous metal is an aluminum alloy. The first temperature is set to 650°C to 720°C, which is suitable for casting molten aluminum alloy products. The second temperature is set to 750°C, and the heat of the molten metal, which is about 100°C higher than the first temperature, is used to efficiently melt and heat the non-ferrous metal introduced from the inlet 11 in a short time. The first and second temperatures can be varied depending on the type of non-ferrous metal being melted and heated.

[0033] In this circulating non-ferrous metal melting furnace, the control unit 100 controls the temperature in each of the first heating chamber 12, the second heating chamber 13, and the tapping chamber 14, and circulates the molten metal via the circulation pump 20. This circulating non-ferrous metal melting furnace 1, which has an unprecedentedly large melting capacity in a small volume, sets the control temperature of the first heating chamber 12 lower than the control temperature of the tapping chamber 14, thereby enabling efficient melting and heating of non-ferrous metal materials. Furthermore, since it is assumed that the control temperature of the first heating chamber 12 is set lower than the control temperature of the tapping chamber 14, planned temperature control can be achieved without placing an excessive load on the first electric heater 30.

[0034] Furthermore, the molten metal is circulated by the circulation pump 20 through the circulation path formed by the first heating chamber 12 and the second heating chamber 13. A portion of the molten metal, which has been heated to a predetermined temperature (first temperature) by the first electric heater 30 in the first heating chamber 12, is received in the tapping chamber 14. In addition, the molten metal from the first heating chamber 12 is heated to a temperature exceeding the predetermined temperature (second temperature) by the second electric heater 40 in the second heating chamber 13, and then circulated back to the first heating chamber 12. Thus, the non-ferrous metal material introduced into the first heating chamber 12 from the input port 11 can be efficiently melted and heated.

[0035] In other words, the molten metal heated to the second temperature (which is hotter than the first temperature) is used to melt the non-ferrous metal material introduced into the first heating chamber 12 and raise its temperature to the first temperature. This allows the non-ferrous metal material to be melted efficiently in a short time and to be heated to a predetermined temperature.

[0036] In this embodiment of the present invention, the inlet 11 for non-ferrous metal materials is provided on the downstream side of the second heating chamber 13 (first inlet 11), but as shown in Figure 1, the second inlet 21 can also be provided on the upstream side of the first heating chamber 12. By providing two input ports 11 and 21 for non-ferrous metal materials, a large surface area of ​​the non-ferrous metal material in contact with the circulating molten metal can be secured, allowing for efficient melting of the non-ferrous metal material.

[0037] Furthermore, by using the non-ferrous metal material inlet ports 11 and 21, or in combination with them, as shown in Figure 2, non-ferrous metal materials can be freely introduced into areas with high or low flow velocity according to the velocity distribution of the circulating molten metal, for example, by using robot arms R1 and R2. According to this, the difference between the upstream and downstream molten metal temperatures in the first heating chamber 12, and the difference between the upstream and downstream molten metal temperatures in the second heating chamber 13, can be minimized as much as possible.

[0038] Furthermore, in this embodiment of the present invention, a gap passage 17a is provided on the upstream side of the second heating chamber 13, and the molten metal is flowed to the tapping chamber 14 via the guide channel 18. However, the invention is not limited to this, and as shown in Figure 2, a gap passage 17a can also be provided on the downstream side of the first heating chamber 12, and the molten metal is flowed to the tapping chamber 14 via the guide channel 18. Alternatively, the guide channel 18, which is equipped with the degassing device 70, can be omitted, and the gap passage 17a can be directly connected to the tapping chamber 14.

[0039] In the above embodiments of the present invention, aluminum alloys are used for melting and heating, but other non-ferrous alloys can also be used. Furthermore, the first and second temperatures can be appropriately changed depending on the non-ferrous metal being targeted. [Explanation of Symbols]

[0040] 1 Circulating non-ferrous metal melting furnace 10 Furnace body 10a Furnace wall 11 Inlet (first inlet) 12. First Temperature-Boosting Chamber 13. Second Temperature-Boosting Chamber 14 Hot spring room 15 Intermediate wall 16 Interstitial path 16a First gap path 16b Second gap path 17 Bulkhead 17a Gap passage 18 Channel 20 Circulation pump 21 Second input port 30 Daiichi Electric Heater 40 Second Electric Heater 50 Circulating non-ferrous metal melting furnace 51 Melting chamber 52 Warming room 53 Debris Removal Room 54 Sedation Room 55 Hot spring room 56 Electric heater 60 Third Electric Heater 70 Degassing equipment 100 Control Unit 101 Circulating non-ferrous metal melting furnace 110 Furnace body 110a Furnace wall 111 Inlet 112 First Temperature-Boosting Room 113 Second Temperature-Boosting Room 114 Hot Spring Room 115 Intermediate wall 117 Bulkhead 117a Gap passage 120 Circulation pump 130 Daiichi Electric Heater 140 Second Electric Heater R1, R2 Robot Arms T1~T11 Thermometer

Claims

1. A circulating non-ferrous metal melting furnace that melts non-ferrous metal materials using an electric heater, A furnace body comprising: an inlet for non-ferrous metal material; a first heating chamber communicating with the inlet; a second heating chamber arranged parallel to the first heating chamber via an intermediate wall, forming a circulation path for molten metal to circulate between the first heating chamber and the second heating chamber; and a tapping chamber located between the first heating chamber and the second heating chamber, communicating with the downstream side of the first heating chamber or the upstream side of the second heating chamber, which receives a portion of the molten metal heated to a predetermined temperature in the first heating chamber and from which the molten metal can be removed; A circulation pump is provided in the first heating chamber or the second heating chamber or both, for circulating the molten metal, The first heating chamber is provided with a plurality of first electric heaters for heating the molten metal to a predetermined first temperature, A plurality of second electric heaters are provided in the second heating chamber, which raise the molten metal that has been heated to a first temperature in the first heating chamber to a second temperature that exceeds the first temperature, Multiple third electric heaters are provided in the aforementioned hot water outlet chamber, The system includes a control unit capable of controlling the output of the first electric heater, the second electric heater, and the third electric heater, respectively. The control unit controls the output of the first electric heater, the second electric heater, and the third electric heater, respectively, so that the control temperature of the first heating chamber is lower than the control temperature of the hot water outlet chamber, and circulates the molten metal heated to a second temperature in the second heating chamber back to the first heating chamber, thereby transferring its heat to the non-ferrous metal material introduced from the inlet.

2. The circulating non-ferrous metal melting furnace according to claim 1, characterized in that the non-ferrous metal material is aluminum or an aluminum alloy.

3. A method for melting non-ferrous metal materials using a circulating non-ferrous metal melting furnace, wherein a first heating chamber equipped with multiple first electric heaters and a second heating chamber equipped with multiple second electric heaters are arranged side by side with an intermediate wall in between to form a circulation path for molten metal, an inlet for non-ferrous metal materials is provided at one end of the intermediate wall between the first heating chamber and the second heating chamber, and a gap passage is provided at the other end of the intermediate wall between the first heating chamber and the second heating chamber that connects to a tapping chamber from which molten metal can be extracted and which is equipped with multiple third electric heaters, and the temperature is controlled in each of the first heating chamber, the second heating chamber, and the tapping chamber, and the molten metal is circulated via a circulation pump provided in the first heating chamber or the second heating chamber or both, wherein the non-ferrous metal material is melted using a circulating non-ferrous metal melting furnace, With the control temperature of the first heating chamber set lower than the control temperature of the hot water outlet chamber, A method for melting non-ferrous metals, characterized in that the non-ferrous metal material is introduced from the input port, heated to a predetermined first temperature in the first heating chamber, a portion of the molten metal heated to the first temperature is received in the outlet chamber, the remainder of the molten metal is received in the second heating chamber, heated to a second temperature exceeding the first temperature by the second electric heater, and then circulated back to the first heating chamber, and the heat of the molten metal circulated back to the first heating chamber is transferred to the non-ferrous metal material newly introduced from the input port.

4. The method for dissolving non-ferrous metals according to claim 3, characterized in that the non-ferrous metal material is aluminum or an aluminum alloy.

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