Circulation type nonferrous metal melting furnace and nonferrous 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

[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 the purpose of using them in the production of various cast products such as die-cast 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 the molten metal has been 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 slag 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 slag removal chamber 53 to the heating chamber 52, but no electric heater is provided in this slag 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 excellent in terms of thermal efficiency and the environment compared to the conventional melting furnace using a gas burner.

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

[0006] As shown in FIG. 4, this cyclic non-ferrous metal melting furnace 101 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 in parallel with the first heating chamber 112 via an intermediate wall 115, and a circulation path formed between the first heating chamber 112 and the second heating chamber 113 through which the molten metal circulates. The furnace body 110 has a tapping chamber 114 that communicates with the downstream side of the first heating chamber 112 between the first heating chamber 112 and the second heating chamber 113, receives a part of the molten metal heated to a predetermined temperature in the first heating chamber 112, and can take out the molten metal. It also includes a circulation pump 120 for circulating the molten metal, a plurality of first electric heaters 130 provided in the first heating chamber 112 for heating the molten metal to a predetermined first temperature, and a plurality of second electric heaters 140 provided in the second heating chamber 113 for heating the molten metal heated to the first temperature in the first heating chamber 112 to a second temperature exceeding the first temperature. The molten metal heated to the second temperature in the second heating chamber 113 is circulated to the first heating chamber 112 to transfer its heat to the non-ferrous metal materials introduced from the inlet 111. A partition wall 117 is provided between the first heating chamber 112 and the tapping chamber 114, and a communication passage 117a is formed in this partition wall 117 to communicate the first heating chamber 112 with the tapping chamber 114. The tapping chamber 114 is provided with a mechanism (not shown) for taking out the received molten metal to the outside.

[0007] According to this, the molten metal is circulated in the circulation path formed by the first heating chamber 112 and the second heating chamber 113 by the circulation pump 120. A part of the molten metal heated to a predetermined temperature (first temperature) by the first electric heater 130 in the first heating chamber 112 is received in the tapping chamber 114. Also, the molten metal from the first heating chamber 112 is heated to a temperature (second temperature) exceeding the predetermined temperature by the second electric heater 140 in the second heating chamber 113 and then circulated to the first heating chamber 112. Thus, the non-ferrous metal materials introduced from the inlet 111 into the first heating chamber 112 can be effectively melted and heated.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

[0009] However, since the circulating non-ferrous metal melting furnace 101 shown in FIG. 4 does not actively control the temperature in the hot water chamber 114, the inventors have come to the idea that if the temperature information in the hot water chamber 114 can be used well, non-ferrous metal materials can be melted and heated to a higher temperature more efficiently.

[0010] Therefore, an object of the present invention is to provide a circulating non-ferrous metal melting furnace and a non-ferrous metal melting method capable of efficiently melting and heating non-ferrous metal materials. [Means for Solving the Problems]

[0011] In order to achieve the above object, 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, and an inlet (11) for the non-ferrous metal material, a first heating chamber (12) communicating with the inlet (11), a second heating chamber (13) arranged in parallel with the first heating chamber (12) via an intermediate wall (15), and forming a circulation path through which the molten metal circulates with the first heating chamber (12), and a furnace body (10) having a hot water chamber (14) that communicates between the first heating chamber (12) and the second heating chamber (13) and on the downstream side of the first heating chamber (12) or the upstream side of the second heating chamber (13) to receive a part of the molten metal heated to a predetermined temperature in the first heating chamber (12) and capable of taking out the molten metal; a circulation pump (20) provided in the first heating chamber (12) or the second heating chamber (13) or both to circulate the molten metal; a plurality of first electric heaters (30) provided in the first heating chamber (12) to heat the molten metal to a predetermined first temperature; A plurality of second electric heaters (40) provided in the second heating chamber (13) for heating the molten metal heated to a first temperature in the first heating chamber (12) to a second temperature exceeding the first temperature; A plurality of third electric heaters (60) provided in the hot water outlet chamber (14); A control unit (100) capable of controlling the outputs of the first electric heater (30), the second electric heater (40), and the third electric heater (60) respectively; The control unit (100) controls the outputs of the first electric heater (30), the second electric heater (40), and the third electric heater (60) 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 while circulating the molten metal heated to the second temperature in the second heating chamber (13) to the first heating chamber (12), the heat is given to the non-ferrous metal material introduced from the inlet (11). It is characterized by the above.

[0012] The circulation type 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 non-ferrous metal melting method of the present invention forms a circulation path for molten metal by arranging a first heating chamber (12) provided with a plurality of first electric heaters (30) and a second heating chamber (13) provided with a plurality of second electric heaters (40) side by side with an intermediate wall (15) interposed therebetween. An inlet (11) for non-ferrous metal material is provided on one end side of the intermediate wall (15) between the first heating chamber (12) and the second heating chamber (13), and a gap path (17a) communicating with a hot water outlet chamber (14) provided with a plurality of third electric heaters (60) capable of taking out molten metal is provided on the other end side of the intermediate wall (15) between the first heating chamber (12) and the second heating chamber (13). Temperature control is performed in each of the first heating chamber (12), the second heating chamber (13), and the hot water outlet chamber (14), and the non-ferrous metal material is melted using a circulation type non-ferrous metal melting furnace (1) configured to circulate molten metal through 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 charged from the charging port (11) to form molten metal heated to a predetermined first temperature in the first heating chamber (12). A part of the molten metal heated to the first temperature is received in the hot water outlet chamber (14), and the remainder of the molten metal is received in the second heating chamber (13). After the temperature is raised to a second temperature exceeding the first temperature by the second electric heater (40), it is circulated to the first heating chamber (12), and the heat of the molten metal circulated to the first heating chamber (12) is applied to the non-ferrous metal material newly charged from the charging port (11).

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

[0015] The symbols in the parentheses above indicate the corresponding elements or corresponding matters described in the drawings and the embodiments for carrying out the invention described later.

Effects of the Invention

[0016] According to the present invention, a first heating chamber provided with a plurality of first electric heaters and a second heating chamber provided with a plurality of second electric heaters are arranged side by side with an intermediate wall therebetween to form a circulation path for molten metal. A charging port for non-ferrous metal materials is provided on one end side of the intermediate wall between the first heating chamber and the second heating chamber, and a communication path communicating with a hot water outlet chamber capable of taking out molten metal and provided with a plurality of third electric heaters is provided on the other end side of the intermediate wall. Temperature control is performed in each of the first heating chamber, the second heating chamber, and the hot water outlet chamber, and the molten metal is circulated via a circulation pump. In a circulation type non-ferrous metal melting furnace having a small volume and an extremely large melting capacity not found in the prior art, the control temperature of the first heating chamber is set lower than the control temperature of the hot water outlet chamber. Therefore, the non-ferrous metal material can be efficiently melted and heated. Further, since it is premised that the control temperature of the first heating chamber is set lower than the control temperature of the hot water outlet chamber, planned temperature control can be realized without imposing an excessive burden on the first electric heater.

[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 exceeding the predetermined temperature (second 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. Therefore, this non-ferrous metal material can be efficiently melted in a short time and heated up to the molten metal at a predetermined temperature.

[0019] It is important to set the control temperature of the first heating chamber lower than the control temperature of the tapping chamber for the following reasons. The relationship between the control temperature of the tapping chamber and the control temperature of the first heating chamber is determined by the following factors. That is, in addition to the variation in the temperature of the molten metal 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 variation in the tapping amount, there will still be a temperature variation in the first heating chamber. However, by controlling the output of the third electric heater provided in the tapping chamber, the remaining temperature variation can be reduced. However, since the electric heater has heating capacity but no cooling capacity, in order to improve the temperature controllability of the tapping chamber, it is necessary to constantly set the control temperature of the first heating chamber lower than the control temperature of the tapping chamber. Here, as shown in FIG. 5, the target temperature of the control temperature of the first heating chamber is set lower than the target temperature of the control temperature of the tapping chamber by the following value (the upper variation range of the first heating chamber + the lower variation range of the tapping chamber + the margin δ). Here, the control temperature of the second heating chamber only needs to be higher than the control temperature of the first heating chamber and can be determined independently of the control 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 favorably.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

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

[0023] As shown in FIG. 1, the cyclic non-ferrous metal melting furnace 1 according to the present embodiment melts and raises the temperature of a non-ferrous metal material by using heat while circulating the molten metal and immersing an electric heater, except for its upper end portion, in the molten metal. 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 that controls the entire electrical system.

[0024] The furnace body 10 has a substantially rectangular planar shape formed by a furnace wall 10a, and includes an inlet 11 for a non-ferrous metal material, 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 charging port 11 is provided on the upstream side of the second heating chamber 13. The first heating chamber 12 is provided in communication with the charging port 11 and receives the non-ferrous metal material charged from the charging port 11. The second heating chamber 13 is arranged side by side with the first heating chamber 12 via an intermediate wall 15 and forms a circulation path through which the molten metal circulates with the first heating chamber 12.

[0026] The tapping chamber 14 is provided at a position opposite to the charging port 11 via a diversion channel 18 provided so as to communicate with the upstream side of the second heating chamber 13. The first heating chamber 12 and the second heating chamber 13 and the diversion channel 18 are partitioned by a partition wall 17 except for a gap channel 17a that communicates with the upstream side of the second heating chamber 13. A degassing device 70 that generates an inert gas to adsorb aluminum dross and float it on the upper surface of the molten metal is attached to the diversion channel 18. The aluminum dross is scraped out manually. This tapping chamber 14 is provided with a mechanism (not shown) for taking out the received molten metal to the outside. The charging port 11 for the non-ferrous metal material is provided on one end side of the intermediate wall 15 between the first heating chamber 12 and the second heating chamber 13, and a gap channel 17a communicating with the tapping chamber 14 is provided on the other end side of the intermediate wall 15 between the first heating chamber 12 and the second heating chamber 13.

[0027] Gap channels 16 (a first gap channel 16a and a second gap channel 16b) are formed between the two end portions of the intermediate wall 15 and the furnace wall 10a and the partition wall 17 facing them, respectively. Therefore, the circulation path is formed in the order of the upstream side (charging port 11), the first gap channel 16a, the first heating chamber 12, the second gap channel 16b, and the second heating chamber 13.

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

[0029] The first electric heater 30 is provided in the first temperature-raising chamber 12 and raises the temperature of the molten metal to a predetermined first temperature. A total of 11 first electric heaters 30 are provided in this embodiment, but this number is not limited. The second electric heater 40 is provided in the second temperature-raising chamber 13 and raises the temperature of the molten metal heated to the first temperature in the first temperature-raising chamber 12 to a second temperature exceeding the first temperature. A total of 6 second electric heaters 40 are provided in this embodiment, but this number is not limited either. The third electric heater 60 is provided in the hot water outlet chamber 14 and raises the temperature of the molten metal in the hot water outlet chamber 14. A total of 4 third electric heaters 60 are provided in this embodiment, but this number is not limited.

[0030] The thermometers T1 to T11 are thermocouple-type sensors, which are respectively provided in the first temperature-raising chamber 12, the second temperature-raising chamber 13, and the hot water outlet chamber 14 to measure the temperature of the molten metal. This number is not limited either.

[0031] Although not shown, the control unit 100 includes a storage unit such as a CPU, a ROM, and a RAM, and controls the circulation pump 20, the first electric heater 30, the second electric heater 40, and the third electric heater 60 based on the temperature information from the input thermometers T1 to T11 and the information of the non-ferrous metal material.

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

[0033] According to the cyclic non-ferrous metal melting furnace configured as described above, in the cyclic non-ferrous metal melting furnace 1 with a small volume and an unprecedentedly large melting capacity, where the control unit 100 performs temperature control in each of the first heating chamber 12, the second heating chamber 13, and the hot water outlet chamber 14 and circulates the molten metal through the circulation pump 20, the control temperature of the first heating chamber 12 is set lower than the control temperature of the hot water outlet chamber 14. Therefore, the non-ferrous metal material can be efficiently melted and heated. Also, since it is premised that the control temperature of the first heating chamber 12 is set lower than the control temperature of the hot water outlet chamber 14, planned temperature control can be achieved without overburdening the first electric heater 30.

[0034] Then, in the circulation path formed by the first heating chamber 12 and the second heating chamber 13, the molten metal is circulated by the circulation pump 20. A part of the molten metal heated to a predetermined temperature (first temperature) by the first electric heater 30 in the first heating chamber 12 is received in the hot water outlet chamber 14, and 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. Therefore, the non-ferrous metal material introduced into the first heating chamber 12 from the inlet 11 can be efficiently melted and heated.

[0035] 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 12 and heat it to the first temperature. Therefore, this non-ferrous metal material can be efficiently melted in a short time and heated to the molten metal at a predetermined temperature.

[0036] In the embodiment of the present invention, although the inlet 11 for the non-ferrous metal material is provided on the downstream side of the second heating chamber 13 (first inlet 11), as shown in FIG. 1, a second inlet 21 can also be provided on the upstream side of the first heating chamber 12. If the inlets 11 and 21 for the non-ferrous metal material are provided at two locations, the surface area of the non-ferrous metal material in contact with the circulating molten metal can be ensured to be large, and the non-ferrous metal material can be efficiently melted.

[0037] Alternatively, or in combination, instead of the non-ferrous metal material inlets 11 and 21, as shown in FIG. 2, the non-ferrous metal material can be freely introduced into the fast-flowing or slow-flowing parts according to the velocity distribution of the circulating molten metal by using, for example, robot arms R1 and R2. According to this, the difference between the molten metal temperature on the upstream side and the downstream side of the first heating chamber 12 and the difference between the molten metal temperature on the upstream side and the downstream side of the second heating chamber 13 can be minimized as much as possible.

[0038] In the 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 caused to flow into the tapping chamber 14 through the flow guide passage 18. However, the present invention is not limited to this. As shown in FIG. 2, a gap passage 17a can be provided on the downstream side of the first heating chamber 12, and the molten metal can be caused to flow into the tapping chamber 14 through the flow guide passage 18. Further, the flow guide passage 18 provided with the degassing device 70 can be omitted, and the gap passage 17a can be directly communicated with the tapping chamber 14.

[0039] In the above embodiment of the present invention, an aluminum alloy is the object of melting and heating, but other non-ferrous alloys can be the object. Further, the first temperature and the second temperature can be appropriately changed according to the non-ferrous metal or the like to be treated.

Explanation of reference numerals

[0040] 1 Circulating non-ferrous metal melting furnace 10 Furnace body 10a Furnace wall 11 Inlet (first inlet) 12 First heating chamber 13 Second heating chamber 14 Tapping chamber 15 Intermediate wall 16 Gap passage 16a First gap passage 16b Second gap passage 17 Partition wall 17a Gap passage 18 Flow guide passage 20 Circulation pump 21 Second inlet 30 First electric heater 40 Second electric heater 50 Circulating non-ferrous metal melting furnace 51 Melting chamber 52 Heating-up chamber 53 Dross removal chamber 54 Calming chamber 55 Hot water outlet chamber 56 Electric heater 60 Third electric heater 70 Degassing device 100 Control unit 101 Circulating non-ferrous metal melting furnace 110 Furnace body 110a Furnace wall 111 Inlet 112 First heating-up chamber 113 Second heating-up chamber 114 Hot water outlet chamber 115 Intermediate wall 117 Partition wall 117a Gap passage 120 Circulation pump 130 First electric heater 140 Second electric heater R1, R2 Robot arm T1~T11 Thermometer

Claims

1. A circulating non-ferrous metal melting furnace that melts non-ferrous metal materials using an electric heater, comprising an inlet for the non-ferrous metal material, a first heating chamber communicating with the inlet, a second heating chamber arranged in parallel with the first heating chamber via an intermediate wall and forming a circulation path through which the molten metal circulates with the first heating chamber, and a tapping chamber communicating between the first heating chamber and the second heating chamber and on the downstream side of the first heating chamber or the upstream side of the second heating chamber, receiving a part of the molten metal heated to a predetermined temperature in the first heating chamber and capable of taking out the molten metal; a circulation pump provided in the first heating chamber or the second heating chamber or both, for circulating the molten metal; a plurality of first electric heaters provided in the first heating chamber for heating the molten metal to a predetermined first temperature; a plurality of second electric heaters provided in the second heating chamber for heating the molten metal heated to the first temperature in the first heating chamber to a second temperature exceeding the first temperature; a plurality of third electric heaters provided in the tapping chamber; a control unit capable of controlling the outputs of the first electric heater, the second electric heater, and the third electric heater respectively; the control unit controls the outputs 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 tapping chamber, and circulates the molten metal heated to the second temperature in the second heating chamber to the first heating chamber to supply its heat to the non-ferrous metal material introduced from the inlet. The circulating non-ferrous metal melting furnace is characterized by this.

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 first heating chamber provided with a plurality of first electric heaters and a second heating chamber provided with a plurality of second electric heaters are arranged side by side with an intermediate wall therebetween to form a molten metal circulation path. An inlet for a non-ferrous metal material is provided on one end side of the intermediate wall between the first heating chamber and the second heating chamber. A gap passage communicating with a hot water outlet chamber provided with a plurality of third electric heaters and capable of taking out the molten metal is provided on the other end side of the intermediate wall between the first heating chamber and the second heating chamber. Temperature control is performed in each of the first heating chamber, the second heating chamber, and the hot water outlet chamber, and the molten metal is circulated through a circulation pump provided in the first heating chamber or the second heating chamber or both. A method for melting a non-ferrous metal material using a circulation type non-ferrous metal melting furnace configured as described above, with the control temperature of the first heating chamber set lower than the control temperature of the hot water outlet chamber, the non-ferrous metal material is charged from the inlet to form a molten metal heated to a predetermined first temperature in the first heating chamber. A part of the molten metal heated to the first temperature is received in the hot water outlet chamber, and the remainder of the molten metal is received in the second heating chamber. After being heated to a second temperature exceeding the first temperature by the second electric heater, it is circulated to the first heating chamber, and the heat of the molten metal circulated to the first heating chamber is applied to the non-ferrous metal material newly charged from the inlet. A non-ferrous metal melting method characterized by the above.

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

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