Metal melting furnace

Abstract

To provide a metal melting furnace which achieves both of fuel consumption reduction and safety securing.SOLUTION: A metal melting furnace 1 comprises: material level detection means 18 which is provided at the outside of a melting furnace body 10 and above a material input port 12, and detects the amount of melting material 60 in a melting chamber 14 via the material input port 12; and molten metal level detection means 19 which is provided at the outside of the melting furnace body 10 and above a molten metal pulping-up part 17, and detects the amount of molten metal 70 in the molten metal pumping-up part 17, and further comprises: melting burner control means which controls ON / OFF of a melting burner 13 by the amount of the molten metal 70 in the molten metal pumping-up part 17 detected by the molten metal level detection means 19; and material input control means which controls whether or not the melting material 60 in a material input apparatus 50 can be inputted by the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18 or the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18 and the amount of the molten metal 70 in the molten metal pumping-up part 17 detected by the molten metal level detection means 19.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a metal melting furnace including a melting chamber having a melting burner for melting a melting material and a molten metal pumping section for pumping out the molten metal.

Background Art

[0002] Conventionally, various metal melting furnaces for melting and holding melting materials (such as aluminum) used in casting and the like are known. In recent years, for such metal melting furnaces, from the viewpoint of reducing working costs and environmental loads, there has been a strong demand for reducing the fuel consumption of various burners used in melting and heat insulation (holding) of melting materials. Under such circumstances, the present applicant has previously proposed a metal melting furnace disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2023-142954) and the like. Patent Document 1 includes a melting chamber (20) for melting a melting material (M1), a molten metal holding chamber (30) having a molten metal storage section (31) for storing the molten metal (M2) melted in the melting chamber (20), and a heating burner (40). The heating burner (40) directly heats and melts the melting material in the melting chamber (20), and indirectly heats and keeps warm the molten metal stored in the molten metal storage section (31) by the burner flame. Patent Document 1 also discloses that a liquid level sensor (57) for detecting the liquid level height of the molten metal (M3) stored in the molten metal pumping section (50) which is arranged in parallel with the molten metal holding chamber (30) and communicated with the molten metal storage section (31) and in which the molten metal (M3) can be pumped out may be provided as necessary. Such a liquid level sensor (57) can be used for operations of countermeasures such as determining an abnormality when the liquid level height of the molten metal (M3) in the molten metal pumping section (50) is detected to be equal to or higher than a predetermined height, activating an alarm device to issue an alarm, or stopping the heating burner (40).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Under such circumstances, the present inventors have found that it is necessary to appropriately manage the state of the melting material in the melting chamber in order to reduce fuel consumption and ensure safety in the metal melting furnace. That is, when there is not an appropriate amount of melting material in the melting chamber (when the melting material is insufficient), even if the melting burner is operated, there is a risk that a desired amount of molten metal cannot be obtained. In addition, when the melting burner is temporarily stopped, preheating the melting material in the melting chamber using the heat (waste heat) stored in the metal melting furnace (melting chamber) in advance contributes to reducing fuel consumption, but there is a risk that such utilization of waste heat (preheating of the melting material) cannot be sufficiently performed. On the other hand, appropriately managing the state of the melting material in the melting chamber is also important from the perspective of safety. That is, when an extremely large amount of molten metal is held in the metal melting furnace (molten metal pumping section), if there is more melting material in the melting chamber than necessary, when the casting line including the metal melting furnace (melting burner) suddenly stops due to an unexpected trouble or the like, although no molten metal is pumped out from the molten metal pumping section, there is a risk that the melting material melted by the waste heat flows out from the melting chamber, and in the worst case, the molten metal may overflow from the molten metal pumping section. Therefore, an object of the present invention is to provide a metal melting furnace including a melting chamber provided with a melting burner for melting a melting material and a molten metal pumping section for pumping out molten metal, in which both reduction of fuel consumption and ensuring of safety are achieved.

Means for Solving the Problems

[0005] What achieves the above object is as follows. (1) A melting furnace body comprising a hearth part, a material inlet for charging a melting material, and a melting burner for melting the melting material on the hearth part charged from the material inlet; a molten metal holding chamber comprising a holding burner for keeping the molten metal melted in the melting chamber warm; and a molten metal pumping part for pumping out the molten metal kept warm in the molten metal holding chamber. A metal melting furnace provided with a material charging device attached to the melting furnace body for charging the melting material from the material inlet. Material level detection means disposed outside the melting furnace body and above the material inlet for detecting the amount of the melting material in the melting chamber through the material inlet; and molten metal level detection means disposed outside the melting furnace body and above the molten metal pumping part for detecting the amount of the molten metal in the molten metal pumping part. A metal melting furnace comprising melting burner control means for controlling ON / OFF of the melting burner according to the amount of the molten metal in the molten metal pumping part detected by the molten metal level detection means; and material charging control means for controlling whether or not to charge the melting material of the material charging device according to the amount of the melting material in the melting chamber detected by the material level detection means or the amount of the melting material in the melting chamber detected by the material level detection means and the amount of the molten metal in the molten metal pumping part detected by the molten metal level detection means.

[0006] (2) The melting burner control means Turns on the melting burner when the amount of the molten metal in the molten metal pumping part detected by the molten metal level detection means is equal to or less than a first molten metal amount set value. The metal melting furnace according to (1) above, which turns off the melting burner when the amount of the molten metal in the molten metal pumping part detected by the molten metal level detection means is greater than the first molten metal amount set value. (3) The material charging control means When the melting burner is in the OFF state, and the amount of molten metal in the molten metal pumping section detected by the molten metal level detection means is equal to or greater than a first molten metal amount set value and equal to or less than a second molten metal amount set value, and the amount of the melting material in the melting chamber detected by the material level detection means is equal to or less than a material amount set value, the input of the melting material by the material input device is permitted. The metal melting furnace according to (2) above, wherein when the melting burner is in the OFF state and the amount of molten metal in the molten metal pumping section detected by the molten metal level detection means is greater than the second molten metal amount set value which is greater than the first molten metal amount set value, the input of the melting material by the material input device is prohibited. (4) The material input control means When the melting burner is in the ON state and the amount of the melting material in the melting chamber detected by the material level detection means is equal to or less than a material amount set value, the input of the melting material by the material input device is permitted. The metal melting furnace according to any one of (1) to (3) above, wherein when the melting burner is in the ON state and the amount of the melting material in the melting chamber detected by the material level detection means is greater than the material amount set value, the input of the melting material by the material input device is prohibited. (5) The melting chamber is provided above the furnace bottom portion and includes a material holding portion which is a cylindrical body having the material input port formed at an upper portion thereof, and the material level detection means detects the height of the melting material in the material holding portion. The metal melting furnace according to any one of (1) to (4) above. (6) The material input device includes a material storage portion for storing plate-shaped melting material plates, a material dividing portion for dividing the melting material plates into a plurality of melting material pieces, and a material input portion for inputting the melting material pieces as the melting material from the material input port. The metal melting furnace according to any one of (1) to (5) above.

Advantages of the Invention

[0007] The metal melting furnace of the present invention comprises a melting furnace body having a hearth section, a material inlet for charging melting materials, a melting burner for melting the melting materials on the hearth section charged from the material inlet, a molten metal holding chamber having a holding burner for holding the molten metal melted in the melting chamber, and a molten metal pumping section for pumping out the molten metal held in the molten metal holding chamber; a material charging device installed in parallel with the melting furnace body for charging melting materials from the material inlet. The metal melting furnace further comprises material level detection means disposed outside the melting furnace body and above the material inlet for detecting the amount of the melting materials in the melting chamber through the material inlet, and molten metal level detection means disposed outside the melting furnace body and above the molten metal pumping section for detecting the amount of the molten metal in the molten metal pumping section. By arranging the material level detection means and the molten metal level detection means in this way, overheating of the material level detection means and the molten metal level detection means can be prevented, malfunctions can be avoided, and detection accuracy can be maintained. Furthermore, the metal melting furnace of the present invention comprises melting burner control means for controlling ON / OFF of the melting burner according to the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means, and material charging control means for controlling whether or not to charge melting materials of the material charging device according to the amount of the melting materials in the melting chamber detected by the material level detection means or according to the amount of the melting materials in the melting chamber detected by the material level detection means and the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means. Thereby, in the metal melting furnace, it is possible to achieve both reduction of fuel consumption and ensuring of safety.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] The metal melting furnace of the present invention will be described using the embodiments shown in the drawings. As shown in FIGS. 1 to 5, the metal melting furnace 1 of the present invention includes a furnace bottom portion 11, a material inlet 12 for charging the melting material 60, a melting burner 13 for melting the melting material 60 on the furnace bottom portion 11 charged from the material inlet 12, a melting chamber 14 having the melting burner 13, a molten metal holding chamber 16 having a holding burner 15 for keeping warm (maintaining in a molten state) the molten metal 70 melted in the melting chamber 14, and a molten metal pumping portion 17 for pumping out the molten metal 70 kept warm in the molten metal holding chamber 16, a melting furnace main body 10 having the molten metal pumping portion 17, and a material charging device 50 installed side by side with the melting furnace main body 10 for charging the melting material 60 from the material inlet 12. Further, the metal melting furnace 1 includes a material level detecting means (sensor) 18 disposed outside the melting furnace main body 10 and above the material inlet 12 for detecting the amount of the melting material 60 in the melting chamber 14 through the material inlet 12, and a molten metal level detecting means (sensor) 19 disposed outside the melting furnace main body 10 and above the molten metal pumping portion 17 for detecting the amount of the molten metal 70 in the molten metal pumping portion 17. The metal melting furnace 1 further includes a melting burner control means for controlling ON / OFF (operation or stop) of the melting burner 13 according to the amount of the molten metal 70 in the molten metal pumping portion 17 detected by the molten metal level detecting means 19, and a material charging control means for controlling whether or not to charge the melting material 60 of the material charging device 50 according to the amount of the melting material 60 in the melting chamber 14 detected by the material level detecting means 18 or the amount of the melting material 60 in the melting chamber 14 detected by the material level detecting means 18 and the amount of the molten metal 70 in the molten metal pumping portion 17 detected by the molten metal level detecting means 19.

[0010] The metal melting furnace 1 (melting furnace main body 10) of the present embodiment is a so-called hand-held melting furnace for melting and holding aluminum molten metal for aluminum casting. Further, the metal melting furnace 1 (melting furnace main body 10) of the present embodiment is generally called a dry hearth furnace.

[0011] The melting chamber 14 of the melting furnace body 10 includes a furnace bottom part 11, a material inlet 12 for charging the melting material 60, and a melting burner 13 for melting the melting material 60 on the furnace bottom part 11 charged from the material inlet 12. The melting chamber 14 is provided with a working inspection port 20 for enabling cleaning etc. inside the melting chamber 14. Normally, the working inspection port 20 is closed by a door 21.

[0012] The furnace bottom part 11 of the melting chamber 14 is open to the molten metal flow lower part 22 side described later, and the other parts are surrounded by a furnace wall that constitutes the outer wall of the melting furnace body 10. The melting chamber 14 is provided adjacent to the furnace bottom part 11 and includes a molten metal flow lower part 22 for temporarily storing the melted melting material 60 (molten metal 70) flowing down from the furnace bottom part 11.

[0013] The furnace bottom part 11 has a horizontal part 23 formed as a substantially horizontal plane, and it is suppressed that the charged melting material 60 accidentally falls into the molten metal flow lower part 22 without being melted. An inclined part 24 that inclines downward toward the horizontal part 23 is formed in the part of the furnace bottom part 11 on the side opposite to the molten metal flow lower part 22 (the right side part in FIG. 4). Thereby, the melted melting material 60 (molten metal 70) on the furnace bottom part 11 flows down toward the molten metal flow lower part 22 via the inclined part 24 and the horizontal part 23. In addition, an inclined part for flowing down the melted melting material 60 (molten metal 70) toward the molten metal flow lower part 22 may be further formed in the part of the furnace bottom part 11 (horizontal part 23) on the molten metal flow lower part 22 side.

[0014] In this embodiment, the melting chamber 14 includes a material holding portion 25 which is a cylindrical body provided above the hearth portion 11 and has a material inlet 12 formed in its upper portion. More specifically, in this embodiment, the material holding portion 25 is composed of a first material holding member 25a which is a cylindrical body substantially entirely accommodated within the melting chamber 14 and has a substantially identical cross-sectional shape over its entire length, and a second material holding member (hopper) 25b which is connected to the upper portion of the first material holding member 25a and is a cylindrical body whose cross-sectional shape expands upward. The material holding portion 25 (the first material holding member 25a and the second material holding member 25b) is open at both the upper and lower portions, and the melting material 60 introduced from the upper opening portion (here, the upper opening portion of the second material holding member 25b, which is the material inlet 12) is supplied onto the hearth portion 11 within the melting chamber 14 from the lower opening portion (here, the lower opening portion of the first material holding member 25a, which opens into the melting chamber 14). It should be noted that, as shown in FIG. 2, in this embodiment, the state of the melting material 60 within the melting chamber 14 is schematically represented and attention needs to be paid to this fact.

[0015] In addition, the metal melting furnace (melting furnace body) may be provided with a material holding portion composed only of a member corresponding to the above-described first material holding member. In that case, the upper opening portion of such a material holding portion (first material holding member) serves as the material inlet. Also, the member corresponding to the above-described second material holding member (hopper) may be removable with respect to the melting furnace body. In that case, when the second material holding member (hopper) is attached, its upper opening portion can be regarded as the material inlet, and when it is removed, the upper opening portion of the first material holding member can be regarded as the material inlet. Also, the member corresponding to the above-described second material holding member (hopper) may be configured as a part of the material feeding device. In that case, when the second material holding member (hopper) is disposed above the melting chamber, in the state where the second material holding member (hopper) is regarded as a part constituting the melting chamber, its upper opening portion can be temporarily regarded as the material inlet. It should be noted that, in this case, the second material holding member (hopper) does not necessarily need to be strictly connected to the first material holding member or the furnace wall portion of the melting furnace body (in other words, there may be a slight gap). Further, the metal melting furnace (melting furnace body) may not be provided with a material holding part in the shape of a cylinder, and the furnace wall part of the melting furnace body that opens upward may serve as the material charging port. Even in such a case, in order to smoothly charge the material, it is possible to attach a member corresponding to the above-described second material holding member (hopper). Note that the material of the above-described material holding part 25 (first material holding member 25a, second material holding member 25b) may be different from the material of the furnace wall of the melting furnace body 10.

[0016] The melting burner 13 is arranged on the furnace wall constituting the outer wall of the melting chamber 14 so as to be able to radiate the burner flame toward the furnace bottom part 11. This melting burner 13 radiates the burner flame toward the melting material 60 in the melting chamber 14 (on the furnace bottom part 11), and directly heats and melts the melting material 60.

[0017] Note that as long as the melting burner 13 can directly heat the melting material 60 in the melting chamber 14 (on the furnace bottom part 11), the burner flame may be radiated from any direction toward the melting material 60. In other words, the melting burner 13 may be arranged on any furnace wall part of the melting chamber 14. Note that the melting burner 13 is preferably arranged at a position facing the inclined part 24 of the furnace bottom part 11 and at a position higher than the furnace bottom part 11 of the melting chamber 14.

[0018] By radiating the burner flame of the melting burner 13 toward the furnace bottom part 11, the furnace bottom part 11 (horizontal part 23 and inclined part 24) located on the burner flame radiation direction side is directly or indirectly heated. Thereby, the melting material 60 on the furnace bottom part 11 can be efficiently melted, and heat can be stored in the melting chamber 14 including the furnace bottom part 11 and used as waste heat. Note that the furnace wall part (part or all) of the melting chamber 14 including the furnace bottom part 11 and the material holding part 25 can be configured with the same material as the other furnace wall parts of the melting furnace body 10, but by using refractory bricks or the like having higher heat storage properties, the heat from the burner flame of the melting burner 13 can be more effectively stored (waste heat can be more effectively used).

[0019] The melting furnace body 10 includes a melting chamber 14 and a molten metal holding chamber 16 provided via a partition wall portion 26. The molten metal holding chamber 16 has a molten metal storage portion 27 that holds (stores) the molten metal 70 temporarily stored in the lower part 22 of the molten metal flow in the melting chamber 14. The melting chamber 14 (lower part 22 of the molten metal flow) and the molten metal holding chamber 16 (molten metal storage portion 27) communicate with each other via a communication passage 28 formed at the lower part of the partition wall portion 26. The depth, width, etc. of the molten metal storage portion 27 are appropriately set according to the size of the metal melting furnace 1 (melting furnace body 10), the desired storage amount of the molten metal 70, etc. Note that the molten metal holding chamber 16 is provided with a work inspection port 29 for enabling cleaning, etc. inside the molten metal holding chamber 16. Normally, the work inspection port 29 is closed by a door 30.

[0020] In this embodiment, the bottom surface of the melting chamber 14 (lower part 22 of the molten metal flow) and the bottom surface of the molten metal holding chamber 16 (molten metal storage portion 27) are substantially on the same plane. However, the bottom surface of the molten metal holding chamber 16 (molten metal storage portion 27) may be formed to be lower than the bottom surface of the melting chamber 14 (lower part 22 of the molten metal flow). In that case, the bottom surface of the communication passage 28 may be an inclined surface that slopes downward toward the molten metal holding chamber 16 (molten metal storage portion 27).

[0021] The molten metal holding chamber 16 includes a holding burner 15 for keeping the melt (molten metal 70) heated and melted in the melting chamber 14 at a predetermined temperature. In this embodiment, the holding burner 15 is arranged on the furnace wall at the upper part of the molten metal holding chamber 16 so as to be able to radiate the burner flame toward the molten metal 70. Note that the holding burner 15 may be arranged on any furnace wall portion of the molten metal holding chamber 16 as long as it can keep the molten metal 70 in the molten metal holding chamber 16 (molten metal storage portion 27) at a predetermined temperature.

[0022] As shown in FIGS. 1 and 4, an exhaust gas flow passage 31 is formed at the upper part of the partition wall portion 26 between the melting chamber 14 and the molten metal holding chamber 16. Such an exhaust gas flow passage 31 is for flowing the exhaust gas from the molten metal holding chamber 16 (the heat of the burner flame radiated by the holding burner 15) effectively. In this embodiment, the heat of the holding burner 15 disposed in the molten metal holding chamber 16 keeps the molten metal in the molten metal holding chamber 16 at a predetermined temperature, and then, as exhaust gas, it flows through the exhaust gas flow passage 31 of the partition wall portion 26 into the melting chamber 14 and is discharged to the outside from the material charging port 12 which also serves as an exhaust port.

[0023] As shown in FIGS. 1 to 3, the metal melting furnace 1 is provided with a molten metal pumping-out portion 17 capable of pumping out the molten metal 70. The molten metal pumping-out portion 17 is arranged in parallel with the molten metal holding chamber 16 via the partition wall portion 32. The molten metal pumping-out portion 17 communicates with the molten metal storage portion 27 of the molten metal holding chamber 16 via a communication passage 33 formed at the lower part of the partition wall portion 32. The molten metal pumping-out portion 17 is open upward, and the molten metal 70 is stored so that it can be pumped out.

[0024] In this embodiment, as shown in FIGS. 1 to 3, the melting chamber 14, the molten metal holding chamber 16, and the molten metal pumping-out portion 17 are arranged in series. Note that the metal melting furnace (melting furnace main body) is not limited to such a mode. For example, by arranging the molten metal pumping-out portion in parallel on the side of the molten metal holding chamber (the direction orthogonal to the above-described series direction), the metal melting furnace (melting furnace main body) can be downsized.

[0025] It is preferable to arrange a heater 34 for keeping the molten metal 70 in the molten metal pumping-out portion 17 warm in the molten metal pumping-out portion 17. As such a heater 34, a known immersion heater using electricity, gas, or the like is preferably used. The heater 34 enables temperature control of the molten metal 70 and keeping the molten metal 70 warm when the holding burner 15 is stopped, and can suppress oxidation of the molten metal 70 and reduce metal loss.

[0026] The molten metal extraction section 17 may be provided with a liquid level sensor 35 for directly detecting the liquid level height of the stored molten metal 70 as needed. The liquid level sensor 35 of this embodiment has a contact portion 36 at the lower part. When the liquid level sensor 35 detects that the liquid level height of the molten metal 70 in the molten metal extraction section 17 is equal to or higher than a predetermined height, that is, when the liquid level of the molten metal extraction section 17 contacts the contact portion 36, it determines that it is abnormal and is used to activate countermeasures such as activating an alarm device (not shown) to issue an alarm or stopping the melting burner 13 and the holding burner 15. By providing such a liquid level sensor 35 simultaneously with the molten metal level detection means 19 described later, the safety of the metal melting furnace 1 can be further enhanced. Although not shown, a temperature sensor for measuring the temperature of the molten metal 70 may be arranged in the molten metal extraction section 17 as needed.

[0027] The metal melting furnace 1 includes a material feeding device 50 provided in the melting furnace body 10. In this embodiment, the material feeding device 50 includes a material storage section 51 for storing the plate-shaped melting material plate 61, a material dividing section 52 for dividing the melting material plate 61 into a plurality of melting material pieces 62, and a material feeding section 53 for feeding the melting material pieces 62 as the melting material 60 through the material inlet 12.

[0028] The material storage section 51 is capable of storing the plate-shaped melting material plate 61. In this embodiment, as shown in FIG. 6, the melting material plate 61 is a plate-shaped melting material that is substantially rectangular in plan view, and a plurality of (here, two) grooves 63 extending in a predetermined direction (here, the vertical direction in FIG. 6) are formed on the upper surface. It is preferable that about 2 to 5 such grooves are formed. Also, such grooves may be formed not only in a certain direction but also in a plurality of directions (for example, the vertical direction and the horizontal direction in FIG. 6), and the grooves may intersect each other. Such a melting material plate 61 is relatively easy to manage, transport, and store. In the material storage section 51, the melting material plates 61 are preferably stored in a stacked state in the plate thickness direction.

[0029] The material dividing unit 52 divides the melting material plate 61 into a plurality of melting material pieces 62. In the material feeding device 50, the melting material plate 61 is conveyed from the material storage unit 51 to the material dividing unit 52 by a conveying arm or the like (not shown). The material dividing unit 52 divides the melting material plate 61 into a plurality of melting material pieces 62 by applying a load or impact to the melting material plate 61. In this embodiment, the melting material plate 61 is divided at the groove 63 in the material dividing unit 52 and becomes a plurality (here, three) of melting material pieces 62 as shown in FIG. 8. Note that the division of the melting material plate is not limited to such a mode, and the melting material plate may be divided at a portion other than the groove, or a melting material plate without a groove may be divided into a plurality of melting material pieces having different sizes.

[0030] The material feeding unit 53 feeds the melting material piece 62 as the melting material 60 through the material inlet 12. In the material feeding device 50, the melting material piece 62 is conveyed from the material dividing unit 52 to the material feeding unit 53 by a conveying arm or the like (not shown). The material feeding unit 53 includes a conveying conveyor (not shown), conveys the melting material piece 62 upward, and then feeds it into the melting chamber 14 through the material inlet 12 of the melting furnace main body 10 (here, the upper opening of the above-described material holding unit 25 (second material holding member 25b)).

[0031] As shown in FIGS. 1 and 2, the metal melting furnace 1 includes a molten metal level detecting means 19. In this embodiment, the molten metal level detecting means 19 is disposed outside the melting furnace main body 10 and above the molten metal pumping unit 17. In this embodiment, the molten metal level detecting means 19 is a sensor 19 that indirectly detects the amount of the molten metal 70 (the height of the liquid surface of the molten metal 70) in the molten metal pumping unit 17 from above the molten metal pumping unit 17, and an ultrasonic type or laser type level sensor or the like can be preferably used.

[0032] By arranging the molten metal level detection means (sensor) 19 outside the melting furnace body 10 and above the molten metal pumping section 17, overheating of the molten metal level detection means (sensor) 19 can be prevented, thus preventing malfunctions and maintaining detection accuracy. Note that the molten metal level detection means (sensor) 19 is preferably arranged such that the distance H1 from the upper end of the molten metal pumping section 17 is about 2500 to 3000 mm. Thereby, overheating prevention (malfunction prevention) of the molten metal level detection means (sensor) 19 and maintenance of detection accuracy can be achieved in a well-balanced manner. Further, a configuration for cooling (such as a fan, etc.) may be provided together with the molten metal level detection means (sensor) 19.

[0033] As shown in FIGS. 1 and 2, the metal melting furnace 1 includes a material level detection means 18. In this embodiment, the material level detection means 18 is arranged outside the melting furnace body 10 and above the material charging port 12. In this embodiment, the material level detection means 18 is a sensor 18 that indirectly detects the amount (height of the melting material 60) of the melting material 60 in the melting chamber 14 from above the material charging port 12 through the material charging port 12, and an ultrasonic type or laser type level sensor or the like can be preferably used. More specifically, in this embodiment, the melting chamber 14 of the melting furnace body 10 includes a material holding portion 25 which is a cylindrical body provided above the furnace bottom portion 11 and has a material charging port 12 formed at the upper portion, and the material level detection means 18 detects the height of the melting material 60 (melting material piece 62) in the material holding portion 25.

[0034] Note that when indirectly detecting the height (amount of the melting material 60) of the melting material 60 in the melting chamber 14 from above the material charging port 12 by the material level detection means 18, the height of the highest portion of the melting material 60 (distance from the material level detection means 18) may be detected. Also, the heights (distances from the material level detection means 18) of a plurality of portions of the melting material 60 may be detected, and their average value or median value may be detected as the height of the melting material 60.

[0035] By arranging the material level detection means (sensor) 18 outside the melting furnace main body 10 and above the material charging port 12, overheating of the material level detection means (sensor) 18 can be prevented, failures can be avoided, and detection accuracy can be maintained. Note that the material level detection means (sensor) 18 is preferably arranged such that the distance H2a from the upper end of the material charging port 12 (in this embodiment, the upper end of the second material holding member 25b) is about 1500 to 2000 mm. Thereby, overheating prevention (failure prevention) of the material level detection means (sensor) 18 and maintenance of detection accuracy can be achieved in a well-balanced manner. Also, the material level detection means (sensor) 18 is preferably arranged such that the distance H2b from the upper end of the melting furnace main body 10 excluding the material holding part 25 (the first material holding member 25a and the second material holding member 25b) is about 2000 to 2500 mm.

[0036] Note that during the shutdown of the metal melting furnace 1, in order to increase the heat retention of the molten metal 70 in the melting furnace main body 10 to reduce the operating time of the holding burner 15 and reduce fuel consumption, a lid (not shown) may be placed on the material charging port 12 which is the upper opening of the melting chamber 14. Here, since the material level detection means (sensor) 18 of this embodiment is not arranged inside the melting furnace main body 10 (melting chamber 14), the molten metal 70 in the melting furnace main body 10 can be appropriately heat-retained using the lid without overheating the sensor 18.

[0037] The metal melting furnace 1 includes a melting burner control means (not shown) that controls the ON / OFF (operation or stop) of the melting burner 13 according to the amount of the molten metal 70 in the molten metal pumping part 17 detected by the molten metal level detection means 19, and a material charging control means (not shown) that controls whether or not to charge the melting material 60 (melting material piece 62) of the material charging device 50 according to the amount of the molten metal 70 in the molten metal pumping part 17 detected by the molten metal level detection means 19 and / or the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18.

[0038] The control of the ON / OFF (operation or stop) of the melting burner 13 and the enabling / disabling of the input of the melting material 60 (melting material pieces 62) of the material input device 50 by the melting burner control means and the material input control means will be described below with reference to the flowchart shown in FIG. 9.

[0039] In this embodiment, although detailed description is omitted, the melting burner control means and the material input control means can be incorporated into the control unit 55 provided in the metal melting furnace 1 as schematically shown in FIGS. 1, 2, and 4. The control unit 55 is, for example, a PLC (Programmable Logic Controller; sequencer), an industrial PC, or the like. The control unit 55 is connected to the material level detection means (sensor) 18, the molten metal level detection means (sensor) 19, the melting burner 13, and the material input device 50. The control unit 55 includes an arithmetic processing unit (CPU) that performs arithmetic processing (here, judgment of the ON / OFF (operation or stop) of the melting burner 13 and the enabling / disabling of the input of the melting material 60 (melting material pieces 62) of the material input device 50), a storage unit (memory, storage medium) that stores a control program and the like, an input unit that transmits signals from the predetermined external devices (here, the material level detection means (sensor) 18 and the molten metal level detection means (sensor 19)) to the arithmetic processing unit, and an output unit that transmits signals (arithmetic results) from the arithmetic processing unit to the predetermined external devices (here, the melting burner 13 and the material input device 50). Further, the control unit 55 may include an interface unit for controlling the input / output (communication) of signals with the connected external devices and for adjusting (rewriting) the control program.

[0040] In step S1, when the amount of the molten metal 70 in the molten metal extraction section 17 detected by the molten metal level detection means 19 is equal to or less than the first molten metal amount set value, the melting burner control means turns on the melting burner 13 (shifts to step S1a), and when the amount of the molten metal 70 in the molten metal extraction section 17 detected by the molten metal level detection means 19 is more than the first molten metal amount set value, the melting burner control means turns off the melting burner 13 (shifts to step S1b). Thereby, when the amount of the molten metal is small, the melting of the melting material 60 is advanced in the melting chamber 14 to prevent the molten metal from running out, while when there is a surplus in the amount of the molten metal, by increasing the stop frequency of the melting burner 13, fuel (gas) can be saved and the fuel consumption can be reduced. During the stop of the melting burner 13, the melting material 60 can be preheated by the residual heat in the melting chamber 14.

[0041] When shifting from the above step S1 to step S1a, subsequently shift to step S2. In step S2, when the melting burner 13 is in the ON state (here, the transition state from step S1a) and the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18 is less than or equal to the material amount set value, the material input device 50 is permitted to input the melting material 60 (melting material piece 62) (shift to step S2a). When the melting burner is in the ON state (here, the transition state from step S1a) and the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18 is more than the material amount set value, the input of the melting material 60 (melting material piece 62) of the material input device 50 is prohibited (shift to step S2b). Thereby, even though the amount of the molten metal is small and the melting burner 13 is turned on to prevent the molten metal from running out, when the amount of the melting material 60 in the melting chamber 14 is small, the melting material 60 is positively input into the melting chamber 14, so that so-called dry burning (a state where the heat from the burner flame of the melting burner 13 cannot be sufficiently utilized for melting the melting material 60) can be prevented. Also, when there is a sufficient amount of the melting material 60 in the melting chamber 14 with the melting burner 13 turned on to prevent the molten metal from running out due to the small amount of the molten metal, the input of the melting material 60 into the melting chamber 14 is stopped, and in the event that the metal melting furnace 1 suddenly stops, it is possible to prevent the molten metal from being excessively supplied due to the residual heat and the molten metal from overflowing from the molten metal pumping section 17.

[0042] In step S1, when the amount of the molten metal 70 in the molten metal pumping section 17 detected by the molten metal level detection means 19 is greater than the first molten metal amount set value, the melting burner 13 is turned OFF (shift to step S1b). When shifting to step S1b, subsequently shift to step S3. Step S3 determines whether the amount of the molten metal 70 in the molten metal pumping section 17 detected by the molten metal level detection means 19 is equal to or less than a second molten metal amount set value greater than the first molten metal amount set value used in step S1 or greater than that, and depending on the result, the control shifts to step S2 or step S2b described above. That is, the material input control means is in a state where the melting burner 13 is OFF (here, the shifting state from step S1b), and when the amount of the molten metal 70 in the molten metal pumping section 17 detected by the molten metal level detection means 19 is equal to or less than the second molten metal amount set value greater than the first molten metal amount set value (when shifting from step S3 to step S2), and when the amount of the melting material 60 in the melting chamber 14 detected by the material level detection means 18 is equal to or less than the material amount set value, the input of the melting material 60 (melting material piece 62) of the material input device 50 is permitted (shift to step S2a). When the melting burner 13 is in an OFF state (here, the shifting state from step S1b) and the amount of the molten metal 70 in the molten metal pumping section 17 detected by the molten metal level detection means 19 is greater than the second molten metal amount set value greater than the first molten metal amount set value, the input of the melting material 60 (melting material piece 62) of the material input device 50 is prohibited (shift to step S2b). Thereby, when there is a margin in the amount of the molten metal and the melting burner 13 is turned OFF to reduce fuel consumption, and when there is no risk of the molten metal overflowing from the molten metal pumping section 17 due to the supply degree of the molten metal by the waste heat, when the amount of the melting material 60 in the melting chamber 14 is small, the waste heat in the melting chamber 14 can be more effectively utilized by positively inputting the melting material 60 into the melting chamber 14. Also, when there is a margin in the amount of the molten metal and the melting burner 13 is turned OFF to reduce fuel consumption, and when there is an extremely large amount of molten metal in the molten metal pumping section 17, the input of the melting material 60 into the melting chamber 14 is stopped, and in the event that the metal melting furnace 1 suddenly stops, it is possible to prevent the molten metal from being excessively supplied by the waste heat and the molten metal from overflowing from the molten metal pumping section 17.

[0043] Incidentally, the material amount setting value (first material amount setting value) when shifting from step S1a (the melting burner 13 is in the ON state) to step S2 and the material amount setting value (second material amount setting value) when shifting from step S1b (the melting burner 13 is in the OFF state) to step S2 via step S3 can be set to different numerical values. In this case, it is preferable that the second material amount setting value is larger than the first material amount setting value.

[0044] Incidentally, in the metal melting furnace 1 of this embodiment, the melting material 60 (melting material piece 62) input from the material input device 50 into the melting chamber 14 can be aligned to some extent within the material holding portion 25 which is a cylindrical body (the first material holding member 25a housed in the melting chamber 14). Thereby, the detection of the amount of the melting material 60 in the melting chamber 14 (the height of the melting material 60 in the material holding portion 25) by the material level detection means 18 can be performed more accurately.

[0045] Incidentally, in the metal melting furnace 1 of this embodiment, the material input device 50 is provided with a material dividing portion 52, and after dividing the plate-shaped melting material plate 61 into a plurality of melting material pieces 62, the melting material pieces 62 are input into the melting furnace main body 10 (melting chamber 14) as the melting material 60. Thereby, the filling efficiency of the melting material 60 (melting material piece 62) in the melting furnace main body 10 (melting chamber 14) can be increased, and the detection of the amount of the melting material 60 in the melting chamber 14 (the height of the melting material 60 in the material holding portion 25) by the material level detection means 18 can be performed more accurately. Further, by increasing the filling efficiency of the melting material 60 (melting material piece 62) in the melting furnace main body 10 (melting chamber 14), the utilization of the waste heat in the melting chamber 14 (preheating of the melting material 60) can also be efficiently performed.

[0046] The metal melting furnace of the present invention is not limited to the above-described embodiments. For example, as the material level detection means, instead of the above-described level sensor, a camera that detects the state of the melting material 60 in the melting chamber 14 as an image can also be used. That is, the melting chamber 14 of the metal melting furnace 1 includes a material holding portion 25 that is provided above the furnace bottom portion 11 and is a cylindrical body having a material charging port 12 formed at the upper portion, and the material level detection means can be a camera capable of confirming the state of the melting material 60 from above the material charging port 12. In such a case, the state of the melting material 60 in the melting chamber 14 stored in the control unit in advance is compared with the state of the melting material 60 in the melting chamber 14 actually photographed (detected) by the camera (material level detection means), and the amount of the melting material 60 in the melting chamber 14 can be determined. Further, the relationship between the determination result (the determination result as to whether the amount of the melting material 60 in the melting chamber 14 is more or less than the material amount set value) and the subsequent state of the melting material 60 in the melting chamber 14 and the amount of the molten metal 70 in the molten metal pumping portion 17 detected by the molten metal level detection means 19 is continuously learned, and the material amount set value (including the first material amount set value and the second material amount set value) and the molten metal amount set value (including the first molten metal amount set value and the second molten metal amount set value) can be appropriately changed.

Description of Reference Numerals

[0047] 1 Metal melting furnace 10 Melting furnace body 11 Furnace bottom portion 12 Material charging port 13 Melting burner 14 Melting chamber 15 Holding burner 16 Molten metal holding chamber 17 Molten metal pumping portion 18 Material level detection means 19 Molten metal level detection means 25 Material holding portion 50 Material charging device 51 Material storage portion 52 Material dividing portion 53 Material charging portion 55 Control unit 60 Melting material 70 Molten metal

Claims

1. A melting furnace body comprising a hearth section, a material inlet for charging a melting material, a melting burner for melting the melting material on the hearth section charged from the material inlet, a molten metal holding chamber having a holding burner for holding the molten metal melted in the melting chamber, and a molten metal pumping section for pumping out the molten metal held in the molten metal holding chamber; A metal melting furnace provided with a material charging device that is installed adjacent to the melting furnace body and charges the melting material from the material inlet; Material level detection means disposed outside the melting furnace body and above the material inlet for detecting the amount of the melting material in the melting chamber through the material inlet, and molten metal level detection means disposed outside the melting furnace body and above the molten metal pumping section for detecting the amount of the molten metal in the molten metal pumping section; A metal melting furnace characterized by comprising melting burner control means for controlling ON / OFF of the melting burner based on the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means, and material charging control means for controlling whether or not to charge the melting material of the material charging device based on the amount of the melting material in the melting chamber detected by the material level detection means or the amount of the melting material in the melting chamber detected by the material level detection means and the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means.

2. The melting burner control means: Turns on the melting burner when the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means is equal to or less than a first molten metal amount set value; Turns off the melting burner when the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means is greater than the first molten metal amount set value. The metal melting furnace according to Claim 1.

3. The material charging control means: Permits charging of the melting material of the material charging device when the melting burner is in an OFF state, the amount of the molten metal in the molten metal pumping section detected by the molten metal level detection means is equal to or less than a second molten metal amount set value greater than the first molten metal amount set value, and the amount of the melting material in the melting chamber detected by the material level detection means is equal to or less than a material amount set value. When the melting burner is in the OFF state and the amount of molten metal in the molten metal pumping section detected by the molten metal level detecting means is greater than the second molten metal amount set value which is greater than the first molten metal amount set value, the metal melting furnace according to claim 2, wherein the charging of the melting material by the material charging device is prohibited.

4. The material charging control means When the melting burner is in the ON state and the amount of the melting material in the melting chamber detected by the material level detecting means is less than or equal to the material amount set value, permits the charging of the melting material by the material charging device, When the melting burner is in the ON state and the amount of the melting material in the melting chamber detected by the material level detecting means is greater than the material amount set value, the metal melting furnace according to any one of claims 1 to 3, wherein the charging of the melting material by the material charging device is prohibited.

5. The melting chamber is provided above the furnace bottom portion and includes a material holding portion which is a cylindrical body having the material charging port formed at the upper portion, and the material level detecting means detects the height of the melting material in the material holding portion. The metal melting furnace according to claim 1.

6. The material charging device includes a material storage portion for storing a plate-shaped melting material plate, a material dividing portion for dividing the melting material plate into a plurality of melting material pieces, and a material charging portion for charging the melting material pieces as the melting material through the material charging port. The metal melting furnace according to claim 1.

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