Melting and holding furnace

Abstract

To provide a melting and holding furnace capable of reducing energy consumption.SOLUTION: A melting and holding furnace of the embodiment includes: a melting crucible for melting a metal material to obtain a molten metal; an electric heater for heating the melting crucible; a holding furnace for holding molten metal supplied from the melting crucible, the holding furnace including a temperature raising unit for raising the temperature of the molten metal, a temperature adjusting unit for maintaining the temperature of the molten metal at a predetermined temperature, and a partition plate provided between the temperature raising unit and the temperature adjusting unit and having a communication port through which a lower portion of the temperature raising unit and a lower portion of the temperature adjusting unit communicate with each other; a first immersion heater for heating the molten metal in the temperature raising unit; a second immersion heater for heating the molten metal in the temperature adjusting unit; and a molten metal supply path connected to the melting crucible and supplying the molten metal overflowed from the melting crucible to the temperature raising unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a melting and holding furnace for melting and holding a mold material. [Background technology]

[0002] Die-casting machines manufacture die-cast products by filling the cavity of a mold clamped by a mold clamping device with molten metal obtained by melting a metal material using an injection device. The processes of melting the metal material and holding the molten metal are considered to be the most energy-intensive in the production of die-cast products. Therefore, in today's society striving for carbon neutrality, it is desirable to reduce the energy consumption in the processes of melting the metal material and holding the molten metal.

[0003] Patent Document 1 describes a melting and holding furnace that reduces energy consumption by providing a preheating tower above a melting crucible and using the combustion exhaust gas generated in the melting crucible, which is heated by a gas burner, to preheat the metal material. For example, the melting and holding furnace described in Patent Document 1 suffers from energy loss due to the combustion exhaust gas being discharged from the top of the preheating tower. Furthermore, especially when only a small amount of metal material is charged into the preheating tower, the amount of heat absorbed by the metal material from the combustion exhaust gas is small, resulting in significant energy loss due to the combustion exhaust gas being discharged from the top of the preheating tower. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-214555 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem to be solved by the present invention is to provide a melting and holding furnace that reduces energy consumption. [Means for solving the problem]

[0006] A melting and holding furnace according to one embodiment of the present invention comprises: a melting crucible for melting a metal material to produce a molten metal; an electric heater for heating the melting crucible; a holding furnace for holding the molten metal supplied from the melting crucible, the holding furnace including a temperature-raising section for raising the temperature of the molten metal; a temperature-regulating section for maintaining the temperature of the molten metal at a predetermined temperature; and a partition plate disposed between the temperature-raising section and the temperature-regulating section and having a communication port for connecting a lower portion of the temperature-raising section with a lower portion of the temperature-regulating section; a first immersion heater for heating the molten metal in the temperature-raising section; a second immersion heater for heating the molten metal in the temperature-regulating section; and a molten metal supply path connected to the melting crucible for supplying the molten metal overflowing from the melting crucible to the temperature-raising section.

[0007] The melting and holding furnace of the above aspect preferably further comprises a housing that encloses the melting crucible, the electric heater, the holding furnace, and the molten metal supply passage.

[0008] The melting and holding furnace of the above aspect preferably further comprises a gas supply passage for supplying an inert gas into the housing.

[0009] In the melting and holding furnace of the above aspect, it is preferable that the first immersion heater extends vertically within the temperature raising section, and the second immersion heater extends horizontally at the bottom of the temperature adjusting section.

[0010] In the melting and holding furnace of the above aspect, the housing preferably includes an openable and closable metal material inlet provided directly above the melting crucible.

[0011] The melting and holding furnace of the above aspect preferably further comprises a metal material feeder capable of feeding the metal material from the metal material inlet into the melting crucible.

[0012] In the melting and holding furnace of the above aspect, the metal material feeder preferably includes a preheater that heats the metal material.

[0013] The melting and holding furnace of the above aspect preferably further comprises a melt level detector that detects the height of the molten metal surface in the temperature adjustment section.

[0014] In the melting and holding furnace of the above aspect, it is preferable that the melting and holding furnace further comprises a melt level detector that detects the height of the molten metal surface in the temperature control unit, and a control unit that controls the metal material supply machine, and when the melt level detected by the melt level detector reaches a predetermined lower limit value, the control unit controls the metal material supply machine to start pouring the metal material into the melting crucible, and when the melt level detected by the melt level detector reaches a predetermined upper limit value, the control unit controls the metal material supply machine to stop pouring the metal material into the melting crucible.

[0015] The melting and holding furnace of the above aspect preferably further comprises a molten metal discharge passage for discharging the molten metal in the temperature adjustment section to the outside of the housing.

[0016] In the melting and holding furnace of the above aspect, it is preferable that a filter is provided at the communication port. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a melting and holding furnace that reduces energy consumption. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a melting and holding furnace according to a first embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the operation of the melting and holding furnace of the first embodiment. [Figure 3] FIG. 2 is a schematic cross-sectional view showing the operation of the melting and holding furnace of the first embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view showing the operation of the melting and holding furnace of the first embodiment. [Figure 5] FIG. 4 is a schematic cross-sectional view showing a melting and holding furnace according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0020] (First embodiment) The melting and holding furnace of the first embodiment includes a melting crucible for melting a metal material to produce molten metal, an electric heater for heating the melting crucible, and a holding furnace for holding the molten metal supplied from the melting crucible, the holding furnace including a temperature rising section for raising the temperature of the molten metal, a temperature control section for maintaining the temperature of the molten metal at a predetermined temperature, and a partition plate provided between the temperature rising section and the temperature control section and having a communication port for connecting the lower part of the temperature rising section with the lower part of the temperature control section; a first immersion heater for heating the molten metal in the temperature rising section; a second immersion heater for heating the molten metal in the temperature control section; and a molten metal supply path connected to the melting crucible for supplying molten metal overflowing from the melting crucible to the temperature rising section.

[0021] 1 is a schematic cross-sectional view showing a melting and holding furnace according to a first embodiment. The melting and holding furnace according to the first embodiment is a melting and holding furnace 100. The melting and holding furnace 100 has the functions of melting a metal material to form a molten metal and maintaining the molten metal at a predetermined temperature.

[0022] The melting and holding furnace 100 includes a melting crucible 10, a molten metal supply passage 12, an electric heater 14, a holding furnace 20, a first immersion heater 31, a second immersion heater 32, a housing 34, a molten metal discharge passage 36, a gas supply passage 38, a molten metal level detector 40, a first thermometer 41, a second thermometer 42, and a third thermometer 43.

[0023] The holding furnace 20 includes a temperature raising section 21, a temperature adjusting section 22, a partition plate 23, and a filter 24. The partition plate 23 has a communication opening 23a.

[0024] The housing 34 includes a metal material inlet 34a and an opening / closing shutter 34b.

[0025] The melting crucible 10 has a function of melting a metal material to form a molten metal 11. The metal material is, for example, a light metal alloy. The metal material is, for example, an aluminum alloy. The metal material is, for example, an ingot.

[0026] The melting crucible 10 is made of, for example, graphite, cast iron, or ceramics.

[0027] The molten metal supply passage 12 is provided on the side surface of the melting crucible 10. The molten metal supply passage 12 has a function of supplying the molten metal that has overflowed from the melting crucible 10 to the temperature raising section 21 of the holding furnace 20.

[0028] The molten metal supply passage 12 has, for example, a trough shape. The molten metal supply passage 12 is made of, for example, graphite, cast iron, or ceramics. The molten metal supply passage 12 may be integrally formed with the melting crucible 10, for example.

[0029] The electric heater 14 is provided around the melting crucible 10. The electric heater 14 has the function of heating the melting crucible 10.

[0030] The electric heater 14 is a heater that uses electrical energy for heating. The electric heater 14 is, for example, an electric heater. The electric heater 14 is, for example, an electromagnetic induction heater.

[0031] The holding furnace 20 has a function of holding the molten metal 11 supplied from the melting crucible 10. The holding furnace 20 includes a temperature raising section 21, a temperature adjusting section 22, and a partition plate .

[0032] The holding furnace 20 is made of, for example, graphite, cast iron, ceramics, or castable refractory material.

[0033] The partition plate 23 is provided between the temperature raising section 21 and the temperature adjusting section 22. The partition plate 23 separates at least the upper part of the temperature raising section 21 from the upper part of the temperature adjusting section 22.

[0034] A communication port 23a is provided in the lower part of the partition plate 23. The communication port 23a communicates the lower part of the temperature raising part 21 with the lower part of the temperature adjusting part 22. The molten metal 11 can move between the temperature raising part 21 and the temperature adjusting part 22 through the communication port 23a.

[0035] By providing the partition plate 23 , for example, impurities such as oxides present on the surface of the molten metal in the temperature raising section 21 are prevented from moving to the temperature adjusting section 22 .

[0036] The filter 24 is provided at the communication port 23a. The filter 24 prevents impurities such as oxides contained in the molten metal 11 in the temperature raising section 21 from moving to the temperature adjusting section 22, for example.

[0037] The temperature raising section 21 has a function of raising the temperature of the molten metal 11 supplied from the melting crucible 10. The molten metal 11 supplied from the melting crucible 10 is heated by the first immersion heater 31.

[0038] The first immersion heater 31 extends, for example, in the vertical direction in the temperature raising section 21. The first immersion heater 31 is an electric heater. The first immersion heater 31 has a heating element that generates heat by electrical energy.

[0039] The temperature control unit 22 has a function of maintaining the molten metal 11 transferred from the temperature raising unit 21 at a predetermined temperature. The temperature control unit 22 has a function of maintaining the molten metal 11 transferred from the temperature raising unit 21 at a predetermined temperature. The predetermined temperature is, for example, 700°C. The molten metal 11 transferred from the temperature raising unit 21 is heated by the second immersion heater 32.

[0040] The second immersion heater 32 extends, for example, horizontally at the bottom of the temperature adjustment unit 22. The second immersion heater 32 is an electric heater. The second immersion heater 32 has a heating element that generates heat by electrical energy.

[0041] The housing 34 encloses the melting crucible 10, the electric heater 14, the holding furnace 20, and the molten metal supply path 12. The housing 34 has a function of isolating the melting crucible 10, the electric heater 14, the holding furnace 20, and the molten metal supply path 12 from the external environment. The housing 34 has a function of shielding the atmosphere inside the housing 34 from the atmosphere outside the housing 34, for example.

[0042] The housing 34 has an openable and closable metal material inlet 34a provided directly above the melting crucible 10. The metal material inlet 34a can be opened and closed by an openable and closable shutter 34b. The openable and closable shutter 34b is driven, for example, by an air cylinder or an electric motor.

[0043] For example, an ingot, which is an example of a metal material, can be charged into the melting crucible 10 through the metal material charging port 34a.

[0044] The housing 34 is made of, for example, metal.

[0045] The molten metal discharge path 36 is provided, for example, to penetrate the housing 34. The molten metal discharge path 36 discharges the molten metal 11 in the temperature adjustment unit 22 to the outside of the housing 34. The molten metal discharged to the outside of the housing 34 is supplied to, for example, an injection device of a die-casting machine (not shown).

[0046] The molten metal discharge passage 36 is, for example, a tubular member. The molten metal discharge passage 36 has, for example, a cylindrical shape that extends linearly in the vertical direction. The molten metal discharge passage 36 is made of, for example, ceramics or metal.

[0047] For example, an electromagnetic pump (not shown) is connected to the molten metal discharge passage 36. For example, the molten metal discharge passage 36 discharges the molten metal 11 from the temperature adjustment unit 22 using the electromagnetic pump.

[0048] The gas supply path 38 is provided, for example, to penetrate the housing 34. The gas supply path 38 has a function of supplying an inert gas into the housing 34. The inert gas is, for example, nitrogen gas or argon gas.

[0049] The gas supply path 38 is, for example, a tubular member. The gas supply path 38 is, for example, cylindrical. The gas supply path 38 is provided with, for example, a mass flow controller for controlling the flow rate of the inert gas.

[0050] The molten metal level detector 40 is provided, for example, on the upper part of the housing 34. The molten metal level detector 40 has a function of detecting the height of the molten metal surface 11 in the temperature adjustment section 22.

[0051] The detection mechanism of the molten metal level detector 40 is not necessarily limited. The molten metal level detector 40 is, for example, an optical sensor. The molten metal level detector 40 optically measures the distance to the surface of the molten metal 11 in the temperature adjustment section 22, for example.

[0052] The molten metal level detector 40 is, for example, a resistance sensor that has a pair of electrodes and is energized to output a signal when the molten metal reaches the position of the electrodes. The molten metal level detector 40 may also be composed of multiple resistance sensors provided at different positions that can detect different molten metal level positions.

[0053] The water level detector 40 may be, for example, a temperature sensor that outputs a signal when the temperature exceeds a predetermined value.

[0054] The first thermometer 41 is provided, for example, on the upper part of the housing 34. The first thermometer 41 has a function of measuring the temperature of the molten metal 11 in the melting crucible 10. The first thermometer 41 is, for example, a thermometer using a thermocouple.

[0055] The result of the temperature measurement by the first thermometer 41 is used, for example, by a control unit (not shown) to control the power input to the electric heater 14. By controlling the power input to the electric heater 14, the temperature of the molten metal 11 in the melting crucible 10 is controlled.

[0056] The second thermometer 42 is provided, for example, on the upper part of the housing 34. The second thermometer 42 has a function of measuring the temperature of the molten metal 11 in the temperature raising section 21. The second thermometer 42 is, for example, a thermometer using a thermocouple.

[0057] The result of the temperature measurement by the second thermometer 42 is used, for example, by a control unit (not shown) to control the power supplied to the first immersion heater 31. By controlling the power supplied to the first immersion heater 31, the temperature of the molten metal 11 in the temperature rising section 21 is controlled.

[0058] The third thermometer 43 is provided, for example, on the upper part of the housing 34. The third thermometer 43 has a function of measuring the temperature of the molten metal 11 in the temperature adjustment unit 22. The third thermometer 43 is, for example, a thermometer using a thermocouple.

[0059] The result of the temperature measurement by the third thermometer 43 is used, for example, by a control unit (not shown) to control the power supplied to the second immersion heater 32. By controlling the power supplied to the second immersion heater 32, the temperature of the molten metal 11 in the temperature adjustment unit 22 is controlled.

[0060] Next, the operation of the melting and holding furnace 100 of the first embodiment will be described.

[0061] 2, 3, and 4 are schematic cross-sectional views showing the operation of the melting and holding furnace of the first embodiment.

[0062] First, the temperature of the molten metal 11 in the melting crucible 10 and the temperature of the molten metal 11 in the holding furnace 20 are controlled to be predetermined temperatures. For example, the temperature of the molten metal 11 in the holding furnace 20 is controlled to be higher than the temperature of the molten metal 11 in the melting crucible 10.

[0063] The molten metal 11 in the melting crucible 10 is also called bottom melt.

[0064] The temperature of the molten metal 11 in the melting crucible 10 and the temperature of the molten metal 11 in the holding furnace 20 vary depending on the metal material used. For example, if the metal material used is ADC12.1, an aluminum alloy, the temperature of the molten metal 11 in the melting crucible 10 is about 600°C, and the temperature of the molten metal 11 in the holding furnace 20 is about 700°C. The melting point of ADC12.1 is 580°C.

[0065] The opening / closing shutter 34b of the housing 34 is kept closed. Nitrogen gas is supplied into the housing 34 from the gas supply line 38, and the atmosphere inside the housing 34 becomes a nitrogen atmosphere.

[0066] Next, as shown in Fig. 2, the opening / closing shutter 34b is opened. Then, the ingot 50 is charged into the melting crucible 10 through the metal material charging port 34a. The ingot 50 is charged into the melting crucible 10 using, for example, a robot arm (not shown). The ingot 50 is an example of a metal material.

[0067] The amount of ingot 50 to be charged is, for example, set so that the amount of molten metal 11 obtained by melting ingot 50 is equal to the amount of molten metal 11 used in one injection operation of the die-casting machine. In other words, the amount of ingot 50 to be charged is set so that the amount of molten metal 11 obtained by melting ingot 50 is equal to the amount of molten metal 11 required to manufacture one die-casting machine product.

[0068] Next, the opening / closing shutter 34b is closed as shown in Fig. 3. The ingot 50 placed in the melting crucible 10 sinks into the molten metal 11 in the melting crucible 10, for example, as shown in Fig. 3. The ingot 50 sinks into the molten metal 11 at the bottom of the melting crucible 10.

[0069] The ingot 50 sinks into the molten metal 11, causing the molten metal 11 to overflow. The overflowed molten metal 11 passes through the molten metal supply path 12 and is supplied to the temperature raising section 21 of the holding furnace 20.

[0070] The low-temperature molten metal 11 supplied to the temperature-raising section 21 is heated by the first immersion heater 31. The molten metal 11 supplied to the temperature-raising section 21 has a temperature of, for example, about 600°C. The heated molten metal 11 passes through the communication port 23a at the bottom of the partition plate 23 and moves to the temperature adjustment section 22.

[0071] The molten metal 11 transferred to the temperature adjustment section 22 is heated by the second immersion heater 32 and maintained at a predetermined temperature. The predetermined temperature is, for example, about 700°C.

[0072] 4, the molten metal 11 in the temperature control unit 22 is discharged from the molten metal discharge path 36 to the outside of the housing 34. The molten metal discharged to the outside of the housing 34 is supplied to, for example, an injection device of a die-casting machine (not shown).

[0073] The melting and holding furnace 100 repeatedly performs the above operations, for example, every time the die-casting machine produces one die-cast product.

[0074] Next, the operation and effects of the melting and holding furnace of the first embodiment will be described.

[0075] Die-casting machines manufacture die-cast products by filling the cavity of a mold clamped by a mold clamping device with molten metal obtained by melting a metal material using an injection device. The processes of melting the metal material and holding the molten metal are considered to be the most energy-intensive in the production of die-cast products. Therefore, in today's society striving for carbon neutrality, it is desirable to reduce energy consumption in the processes of melting the metal material and holding the molten metal.

[0076] The melting and holding furnace 100 of the first embodiment melts an ingot 50 in a melting crucible 10 to form a molten metal 11, heats the resulting molten metal 11 in a temperature-raising section 21 of the holding furnace 20, and keeps the heated molten metal 11 warm in a temperature-regulating section of the holding furnace 20.

[0077] The melting crucible 10 has, for example, the minimum necessary capacity. The minimum necessary capacity is, for example, the capacity for melting the ingot 50 to obtain the amount of molten metal 11 required to produce a single die-cast product.

[0078] By making the melting crucible 10 have the minimum necessary capacity, the amount of energy consumed to heat the melting crucible 10 can be reduced.

[0079] Furthermore, by making the melting crucible 10 have the minimum necessary capacity, it is possible to reduce the size of the melting and holding furnace 100.

[0080] Furthermore, the molten metal 11 supplied from the melting crucible 10 to the holding furnace 20 is heated to a predetermined temperature in the holding furnace 20. Therefore, the molten metal 11 supplied from the melting crucible 10 to the holding furnace 20 can be set to the minimum temperature necessary to maintain its liquid state. For example, the melting crucible 10 is set to be heated to a temperature sufficient to melt one ingot 50. Therefore, the temperature of the molten metal 11 in the melting crucible 10 can be kept low.

[0081] By keeping the temperature of the molten metal 11 in the melting crucible 10 low, the amount of energy consumed to heat the melting crucible 10 can be reduced.

[0082] Furthermore, by using the electric heater 14 as the heat source for the melting crucible 10, the amount of energy consumed to heat the melting crucible 10 can be reduced compared to, for example, gas burner heating, which causes energy loss due to combustion exhaust gas.

[0083] The holding furnace 20 has, for example, the minimum necessary capacity. The minimum necessary capacity is, for example, a capacity that can stably hold the molten metal 11 that is supplied from the melting crucible 10 to the holding furnace 20 at one time.

[0084] By keeping the capacity of the holding furnace 20 to the minimum required, the amount of energy consumed to heat the holding furnace 20 can be reduced.

[0085] Furthermore, by limiting the capacity of the holding furnace 20 to the minimum required, the size of the holding furnace 20 can be reduced.

[0086] The low-temperature molten metal 11 supplied from the melting crucible 10 to the holding furnace 20 is heated and raised in temperature in the temperature-raising section 21 using the first immersion heater 31. Thereafter, the molten metal 11 transferred from the temperature-raising section 21 is heated using the second immersion heater 32 and kept at a predetermined temperature.

[0087] In the melting and holding furnace 100, the holding furnace 20 is separated into a section for raising the temperature of the molten metal 11 and a section for maintaining the temperature of the molten metal 11, and each section is heated by two heaters that are controlled independently. This makes it possible to optimize the amount of energy required to heat the molten metal 11 and reduce the amount of energy consumed to heat the holding furnace 20.

[0088] The first immersion heater 31 preferably extends vertically within the temperature-raising section 21. By extending the first immersion heater 31 vertically, the low-temperature molten metal 11 supplied from the melting crucible 10 to the upper surface of the temperature-raising section 21 can be efficiently heated. This further reduces the amount of energy consumed to heat the holding furnace 20.

[0089] The second immersion heater 32 preferably extends horizontally at the bottom of the temperature control section 22. By having the second immersion heater 32 extend horizontally at the bottom, the molten metal 11 in the temperature control section 22 can be efficiently kept warm by thermal convection. This further reduces the amount of energy consumed to heat the holding furnace 20.

[0090] The melting and holding furnace 100 of the first embodiment can maintain an inert gas atmosphere inside the housing 34 by supplying an inert gas from the gas supply line 38. Maintaining an inert gas atmosphere inside the housing 34 suppresses oxidation of the molten metal 11. Therefore, the quality of the molten metal 11 is improved.

[0091] The melting and holding furnace 100 is capable of maintaining an inert gas atmosphere inside the housing 34 by limiting the heating means for the molten metal 11 to an electric heater.

[0092] As described above, according to the first embodiment, a melting and holding furnace that reduces energy consumption can be realized.

[0093] (Second embodiment) The melting and holding furnace of the second embodiment differs from the melting and holding furnace of the first embodiment in that it further includes a metal material feeder that can feed metal material into the melting crucible through a metal material inlet. Hereinafter, some of the description that overlaps with the first embodiment may be omitted.

[0094] 5 is a schematic cross-sectional view showing a melting and holding furnace according to a second embodiment. The melting and holding furnace according to the second embodiment is a melting and holding furnace 200. The melting and holding furnace 200 has the functions of melting a metal material to form a molten metal and maintaining the molten metal at a predetermined temperature.

[0095] The melting and holding furnace 200 includes a melting crucible 10, a molten metal supply channel 12, an electric heater 14, a holding furnace 20, a first immersion heater 31, a second immersion heater 32, a housing 34, a molten metal discharge channel 36, a gas supply channel 38, a melt level detector 40, a first thermometer 41, a second thermometer 42, a third thermometer 43, a metal material feeder 60, and a control circuit 70 (controller). The control circuit 70 is an example of a controller.

[0096] The holding furnace 20 includes a temperature raising section 21, a temperature adjusting section 22, a partition plate 23, and a filter 24. The partition plate 23 has a communication opening 23a.

[0097] The housing 34 includes a metal material inlet 34a and an opening / closing shutter 34b.

[0098] The metal material feeder 60 is provided above the metal material inlet 34a. The metal material feeder 60 has a function of, for example, feeding an ingot 50, which is a raw material for the molten metal 11, into the melting crucible 10 through the metal material inlet 34a.

[0099] The metal material supply machine 60 includes a preheater 61. The preheater 61 has a function of heating the ingot 50 to a predetermined temperature before it is placed in the melting crucible 10. The preheater 61 is, for example, an electric heater.

[0100] The control circuit 70 controls the metal material supply machine 60. The control circuit 70 controls the metal material supply machine 60 based on the height of the molten metal surface detected by the molten metal surface detector 40, for example.

[0101] When the height of the molten metal surface detected by the molten metal surface detector 40 reaches a predetermined lower limit, the control circuit 70 controls the metal material feeder 60 to start feeding the ingot 50 into the melting crucible 10. When the height of the molten metal surface detected by the molten metal surface detector 40 reaches a predetermined upper limit, the control circuit 70 controls the metal material feeder 60 to stop feeding the ingot 50 into the melting crucible 10.

[0102] The control circuit 70 is configured, for example, by a combination of hardware and software, and includes, for example, a CPU (Central Processing Unit), a semiconductor memory, and a control program stored in the semiconductor memory.

[0103] The melting and holding furnace 200 of the second embodiment is equipped with a metal material supplying machine 60 including a preheater 61. The ingot 50 is heated by the preheater 61 before being charged into the melting crucible 10. For example, the ingot 50 is heated to a temperature close to the melting point before being charged into the melting crucible 10.

[0104] This configuration makes it possible to reduce, for example, the amount of bottom molten metal in the melting crucible 10. Therefore, for example, the amount of energy consumption required to heat the melting crucible 10 can be further reduced.

[0105] In addition, for example, the capacity of the melting crucible 10 can be further reduced, and therefore the size of the melting and holding furnace 200 can be further reduced.

[0106] The control circuit 70 of the melting and holding furnace 200 of the second embodiment controls the metal material feeder 60 based on, for example, the height of the molten metal surface detected by the molten metal surface detector 40. With this configuration, for example, the timing of charging the ingot 50 into the melting crucible 10 is automated, thereby shortening the turnaround time of the operation of the melting and holding furnace 200. Furthermore, for example, it is possible to quickly respond to an abnormality in the height of the molten metal surface.

[0107] As described above, according to the second embodiment, a melting and holding furnace that reduces energy consumption can be realized.

[0108] The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the embodiments, parts of the melting and holding furnace that are not directly necessary for the explanation of the present invention have been omitted, but necessary elements related to the melting and holding furnace can be selected and used as appropriate.

[0109] In addition, all melting and holding furnaces that incorporate the elements of the present invention and that can be appropriately modified by those skilled in the art are encompassed within the scope of the present invention. The scope of the present invention is defined by the claims and their equivalents. [Explanation of symbols]

[0110] 10 Melting crucible 11 Molten metal 12 Molten metal supply channel 14 Electric heater 20 Holding furnace 21 Temperature rising section 22 Temperature control section 23 Partition 23a Communication port 24 filters 31 First immersion heater 32 Second Immersion Heater 34 Case 34a Metal material inlet 34b Open / close shutter 36 Molten metal discharge channel 38 Gas supply line 40 Water level detector 41 First Thermometer 42 Second Thermometer 43 Third Thermometer 50 Ingots (metal materials) 60 Metal material feeder 61 Preheater 70 Control circuit (control section) 100 Melting and holding furnace 200 Melting and holding furnace

Claims

1. a melting crucible for melting a metal material to produce a molten metal; an electric heater for heating the melting crucible; a holding furnace for holding the molten metal supplied from the melting crucible, a temperature raising section that raises the temperature of the molten metal; a temperature control unit that maintains the temperature of the molten metal at a predetermined temperature; a holding furnace including a partition plate provided between the temperature raising section and the temperature adjusting section, the partition plate having a communication opening that connects a lower portion of the temperature raising section and a lower portion of the temperature adjusting section; a first immersion heater that heats the molten metal in the temperature rising section; a second immersion heater that heats the molten metal in the temperature adjustment unit; a molten metal supply passage connected to the melting crucible and configured to supply the molten metal overflowing from the melting crucible to the temperature raising section; A melting and holding furnace comprising:

2. 2. The melting and holding furnace according to claim 1, further comprising a housing that encloses the melting crucible, the electric heater, the holding furnace, and the molten metal supply passage.

3. 3. The melting and holding furnace according to claim 2, further comprising a gas supply passage for supplying an inert gas into the housing.

4. the first immersion heater extends vertically within the temperature rising section; 2. The melting and holding furnace according to claim 1, wherein the second immersion heater extends horizontally at the bottom of the temperature control section.

5. 3. The melting and holding furnace according to claim 2, wherein the housing includes an openable and closable metallic material inlet provided directly above the melting crucible.

6. 6. The melting and holding furnace according to claim 5, further comprising a metal material feeder capable of feeding the metal material into the melting crucible through the metal material feed port.

7. 7. The melting and holding furnace according to claim 6, wherein the metal material feeder includes a preheater for heating the metal material.

8. 2. The melting and holding furnace according to claim 1, further comprising a melt level detector for detecting the height of the molten metal surface in the temperature control section.

9. a melt level detector that detects the height of the melt surface in the temperature control unit; A control unit that controls the metal material supply machine, When the height of the molten metal surface detected by the molten metal surface detector reaches a predetermined lower limit value, the control unit controls the metal material supply device to charge the metal material into the melting crucible, 7. The melting and holding furnace according to claim 6, wherein when the height of the molten metal surface detected by the molten metal surface detector reaches a predetermined upper limit value, the control unit controls the metal material feeder to stop charging the metal material into the melting crucible.

10. 3. The melting and holding furnace according to claim 2, further comprising a molten metal discharge passage for discharging the molten metal in the temperature control section to the outside of the housing.

11. 2. The melting and holding furnace according to claim 1, wherein a filter is provided at the communication port.

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