CN108463680B

CN108463680B - Metal melting device

Info

Publication number: CN108463680B
Application number: CN201780006757.3A
Authority: CN
Inventors: 犬塚史; 村上浩一
Original assignee: Central Motor Wheel Co Ltd
Current assignee: Central Motor Wheel Co Ltd
Priority date: 2016-01-15
Filing date: 2017-01-11
Publication date: 2020-02-21
Anticipated expiration: 2037-01-11
Also published as: CN108463680A; JP6659366B2; WO2017122647A1; JP2017125659A

Abstract

The metal melting apparatus includes: a crucible (20) for storing molten metal therein; a stirring section (30) for stirring the molten metal in the crucible (20); and a heating unit (40) that heats the crucible (20). The stirring section (30) includes: a cylindrical member (32) disposed in the vertical direction at the center of the crucible (20); a plate-like member (31) connected to the upper end of the cylindrical member (32) and arranged in the horizontal direction; a swirling upward flow generating section (33, M1) for generating a swirling upward flow in the molten metal in the cylindrical member (32). An annular gap (Z) is formed between the outer edge of the plate-like member (31) and the inner wall surface of the crucible (20). The interior of the single crucible (20) can be used as a heating chamber and a melting chamber. Therefore, the entire apparatus can be made compact as compared with a system in which the heating chamber and the melting chamber are separately provided.

Description

Metal melting device

Technical Field

The present invention relates to a metal melting apparatus.

Background

Conventionally, a metal melting apparatus for melting a metal material such as an aluminum alloy for use in the production of various cast products is known (for example, see WO 2015/050208). The apparatus described in this document includes a heating chamber for heating molten metal and a melting chamber (vortex chamber) for immersing and melting an introduced metal material by a vortex. The molten metal in the temperature increasing chamber is supplied to the melting chamber by a circulation pump, and the molten metal discharged from the melting chamber is returned to the temperature increasing chamber.

In the apparatus described in the above document, the heating chamber is provided separately from the melting chamber. Therefore, in order to constitute the entire apparatus, a space for installing the heating chamber and a space for installing the melting chamber need to be separately provided, and as a result, the entire apparatus is increased in size.

The present invention has been made to solve the above-described problems, and an object thereof is to provide a metal melting apparatus which can be made compact as a whole.

Disclosure of Invention

The metal melting apparatus of the present invention includes: a crucible having an upper opening and containing a molten metal for melting a metal material; a stirring section configured to stir the molten metal stored in the crucible to generate a flow of the molten metal in the crucible; and a heating unit that heats the crucible.

Thus, the crucible is heated by the heating unit, and the inside of the crucible functions as a temperature increasing chamber. Further, since the molten metal accumulated in the crucible is stirred by the stirring portion, the crucible also functions as a melting chamber (vortex chamber). That is, the inside of a single crucible can be used as a heating chamber and a melting chamber. Therefore, the entire apparatus can be made compact as compared with the apparatus described in the above-mentioned document in which the temperature rising chamber and the melting chamber are separately provided.

In the metal melting apparatus of the present invention, the stirring section preferably includes: a cylindrical member disposed vertically in the molten metal stored in the crucible at a central portion of the crucible when the crucible is viewed from above; and a swirling upward flow generating section that generates a swirling upward flow in which the molten metal located inside the cylindrical member rises while swirling.

Thereby, the molten metal located in the lower portion of the crucible is introduced into the cylindrical member from the lower end portion of the cylindrical member. The molten metal introduced into the tubular member rises while swirling inside the tubular member, and is discharged to the outside of the tubular member through the upper end portion of the tubular member. The molten metal discharged to the outside of the tubular member and located in the upper portion of the crucible interior descends along the inner wall surface of the crucible and returns to the lower portion of the crucible interior. The molten metal returned to the lower portion of the crucible interior is introduced into the tubular member again from the lower end portion of the tubular member. As a result, the molten metal stored in the crucible is easily circulated uniformly throughout the entire crucible.

In the metal melting apparatus according to the present invention, it is preferable that the stirring section includes a plate-like member connected to an upper end portion of the cylindrical member and arranged in a horizontal direction among the molten metal stored in the crucible, and a gap is formed between an outer edge of the plate-like member and an inner wall surface of the crucible.

Thus, a shallow portion having a small depth of the molten metal with the upper surface (horizontal surface) of the plate-like member as the bottom surface is formed continuously in the horizontal direction from the upper end portion of the cylindrical member in the molten metal stored in the crucible. Therefore, the molten metal discharged from the upper end portion of the tubular member while swirling moves to the shoal portion, and after moving to the shoal portion, further swirls in the horizontal plane while spreading toward the outer edge of the plate-like member (therefore, the inner wall surface of the crucible). The molten metal that has reached the outer edge of the plate-like member passes through a gap formed between the outer edge of the plate-like member and the inner wall surface of the crucible, and then descends along the inner wall surface of the crucible.

This structure is preferably applied to a case where "a bulk metal material in an undried state such as a compact obtained by compressing and solidifying a metal powder such as an aluminum cutting powder, that is, a material molded to a size such that the whole is not impregnated when put into a shoal portion" is put into the shoal portion. That is, when such a bulk metal material is put into the shoal portion, the bulk metal material moves in the shoal portion along the flow of the molten metal swirling in the horizontal plane while being melted by the molten metal and gradually reduced in volume in a state where the upper portion thereof is exposed from the molten metal surface of the molten metal. In this process, soot and water vapor from oil and water such as cutting oil adhering to the metal material can be released from the portion of the bulk metal material exposed from the molten metal. Therefore, the drying process is not performed before the metal block is charged, and the oil and water can be safely removed from the metal block.

The bulk metal material, which is reduced in volume and moves over the shoal, reaches the gap shortly after, the volume being reduced to be able to stay in the vicinity of the gap by the size of the gap. When the volume is reduced to a size that can pass through the gap, the bulk metal material passes through the gap and then descends along the inner wall surface of the crucible along the flow of the molten metal circulating inside the crucible.

In the metal melting apparatus according to the present invention, it is preferable that the metal melting apparatus includes a furnace body that houses the crucible therein, and the heating section includes: a burner that heats the crucible by burning a fuel gas in a combustion chamber defined by an outer wall of the crucible and side walls and a bottom wall of the furnace body; and a soot introduction section that guides soot emitted into an upper space defined by the opening of the crucible and the upper wall of the furnace body and derived from oil components contained in the metal material to the combustion chamber.

Accordingly, the soot derived from oil and moisture such as cutting oil adhering to the metal material is guided to the combustion chamber, and the soot guided to the combustion chamber can be burned (post-combustion) in the combustor in the same manner as the fuel gas. Therefore, the soot can be reused as fuel for the burner, and thus energy efficiency is improved. In addition, the oil smoke can be completely combusted to be harmless.

In the metal melting apparatus according to the present invention, it is preferable that the metal melting apparatus includes an input unit for inputting the metal material into the molten metal stored in the crucible, and the input unit is configured to position the metal material on standby in the input unit in a path along which the soot is moved from the upper space to the combustion chamber by the soot introduction unit. Thus, the metal material waiting at the input unit can be subjected to preliminary drying treatment before being input.

Drawings

Fig. 1 is a main sectional view schematically showing a schematic configuration of an embodiment of a metal melting apparatus according to the present invention.

Fig. 2 is a sectional view corresponding to line 2-2 of fig. 1.

Detailed Description

Hereinafter, an embodiment of the metal melting apparatus according to the present invention (hereinafter, referred to as "the present embodiment") will be described with reference to fig. 1 and 2. The present embodiment is used for melting a metal material such as an aluminum alloy with a molten metal. The molten metal material is then used in the manufacture of various cast articles.

(Structure)

As shown in fig. 1 and 2, the present embodiment includes a furnace body 10, a crucible 20 housed inside the furnace body 10, a stirring section 30 for stirring molten metal in the crucible 20, a heating section 40 for heating the crucible 20, and a charging section 50 for making a metal material to be melted stand by.

The furnace body 10 has a bottom wall 11, side walls 12, and an upper wall 13, and covers the entire crucible 20 housed therein. The bottom wall 11, the side walls 12 and the upper wall 13 are made of a heat-resistant material. In this example, the bottom wall 11 is provided integrally with the side wall 12, and the upper wall 13 is provided detachably to the side wall 12. Since the upper wall 13 is detachably attached, the work such as maintenance of the crucible 20 (including replacement of the crucible 20 itself) is easily performed.

A pedestal 18 is provided on the inner surface of the bottom wall 11, and a crucible 20 is disposed on the pedestal 18 so as to be opened at the upper portion. The outer wall of the crucible 20, the bottom wall 11, and the side wall 12 define a combustion chamber S1. The upper space S2 is defined by the opening of the crucible 20 and the upper wall 13.

An exhaust passage 14 for communicating the combustion chamber S1 with the outside is formed in a part of the side wall 12 and the upper wall 13. A passage 15 for introducing secondary air into the exhaust passage 14 is provided in the middle of the exhaust passage 14. The exhaust passage 14 also communicates with the upper space S2 via the passage 16. The upper space S2 communicates with the combustion chamber S1 via the passage 17.

The crucible 20 is a heat-resistant container in a cup shape having an upper opening and arranged in the vertical direction (vertical direction), and high-temperature molten metal is stored in the interior thereof. In this example, the crucible 20 has a rotationally symmetric shape with respect to an axis extending in the vertical direction.

A part of the upper end surface of the crucible 20 constituting the opening is lower than the other part of the upper end surface, and this part is used as a molten metal outlet 21. One end of a spout 22 is connected to the outlet 21. The chute 22 is inclined slightly downward from the outlet 21 and traverses the inside of the exhaust passage 14, and the other end of the chute 22 is exposed to the outside through an opening provided in a part of the side wall 12. A barrier 23 for preventing the metal material charged into the crucible 20 from flowing out of the take-out port 21 immediately before melting is fixed to the upper wall 13 in the vicinity of the take-out port 21.

The stirring section 30 includes a plate member 31, a cylindrical member 32, a stirring rod 33, and a motor M1. The plate-like member 31 is a flat plate having an annular shape in plan view. The plate-like member 31 is suspended from the upper wall 13 by a predetermined suspension tool or the like, and is fixed coaxially with and immovably relative to the crucible 20. The plate-like member 31 is disposed horizontally at a position lower than the height of the outlet 21 by a predetermined amount. An annular gap Z is formed between the outer peripheral edge of the plate-like member 31 and the inner wall surface of the crucible 20.

The cylindrical member 32 is a cylindrical member. The upper end of the cylindrical member 32 is connected and fixed to the inner peripheral edge of the plate-like member 31 over the entire circumference, and the cylindrical member 32 is fixed coaxially with the crucible 20 so as to be immovable relative thereto. The cylindrical member 32 is disposed in the vertical direction (vertical direction) from the inner peripheral edge of the plate member 31 toward the lower side. The lower end of the cylindrical member 32 is in contact with the inner wall surface of the bottom of the crucible 20. At the lower end of the tubular member 32, there are formed inlet ports 32a (4 positions at equal intervals in the circumferential direction in this example) for introducing molten metal outside the tubular member 32 into the tubular member 32.

The stirring rod 33 is a rod-shaped member having a screw 33a at a tip end (lower end). The stirring rod 33 is provided so as to be immovable in the axial direction relative to the upper wall 13 and rotatable in the axial direction, and is disposed coaxially with respect to the crucible 20. The stirring rod 33 is disposed in the vertical direction (vertical direction), and a substantially lower half thereof including the screw 33a is positioned inside the cylindrical member 32. Here, the stirring rod 33 provided with the screw 33a and the motor M1 correspond to the "swirling upward flow generating portion" of the present invention.

The motor M1 is fixed to the upper wall 13 and drives the paddle 33 to rotate around its axis in a predetermined first rotational direction. When the stirring rod 33 rotates in the predetermined first rotation direction, a flow (swirling upward flow) that rises while swirling is generated with respect to the molten metal located inside the cylindrical member 32.

The heating unit 40 includes a burner 41, a fan 42, and a motor M2. The burner 41 is disposed so as to face the combustion chamber S1 at a portion of the side wall 12. The combustor 41 burns the fuel gas in the combustion chamber S1 with the fuel gas and air introduced from the outside through a fuel gas introduction pipe and an air introduction pipe, not shown. The crucible 20 is heated by the combustion heat of the fuel gas.

The fan 42 is provided in the middle of the passage 17 connecting the upper space S2 and the combustion chamber S1. The fan 42 is driven by the motor M2 to rotate in a predetermined second rotational direction. When the fan 42 rotates in the predetermined second rotation direction, a flow is generated from the upper space S2 side to the combustion chamber S1 side with respect to the gas in the passage 17. Here, the fan 42, the motor M2, and the passage 17 correspond to the "soot introduction portion" of the present invention.

The input unit 50 includes an input chute 51 and an impeller 52. The input chute 51 is fixed to the upper wall 13. A passage for moving the metal material is formed inside the input chute 51 with the inlet 51a and the outlet 51b as both ends. The impeller 52 is rotatably provided at a midway position of the passage so as to close the passage. The impeller 52 may be rotated manually or may be rotated electrically by a motor or the like.

The metal material put into the inlet 51a temporarily waits at the position of the impeller 52. The metal material on standby is discharged toward the outlet portion 51b by an amount corresponding to the rotation angle of the impeller 52. The discharged metal material is poured from the outlet portion 51b into the molten metal in the crucible 20 through the opening of the crucible 20.

The impeller 52 positioned in the injection chute 51 is also positioned in the middle of the passage 17 connecting the upper space S2 and the combustion chamber S1. Therefore, the metal material on standby is also located in the middle of the passage 17 at the position of the impeller 52.

The motor M1, the motor M2, and the burner 41 are controlled by a computer shown in fig. 1. That is, the rotation speed of the paddle 33, the rotation speed of the fan 42, and the heating power of the burner 41 are appropriately adjusted and controlled by the computer according to the situation.

(action)

The operation of the present embodiment configured as described above will be described below. In the operation of the present embodiment, the rotation speed of the paddle 33, the rotation speed of the fan 42, and the heat power of the burner 41 are controlled by a computer.

In the operation of the present embodiment, the level of the molten metal stored in the crucible 20 is naturally adjusted to substantially match the height of the outlet 21. That is, when the volume of the molten metal increases due to the melting of the metal material to be charged and the height of the liquid surface of the molten metal exceeds the height of the outlet 21, the molten metal is discharged from the outlet 21 to the outside via the launder 22. As a result, the height of the liquid surface of the molten metal naturally returns to the height of the outlet 21.

In other words, the molten metal can be taken out from the take-out port 21 in an amount corresponding to the amount of the metal material to be charged. The withdrawn molten metal (i.e., molten metal material) is used in the manufacture of various cast products.

As described above, the plate-like member 31 is disposed horizontally at a position lower than the height of the ejection opening 21 by a predetermined amount. The cylindrical member 32 is disposed downward from the inner peripheral edge of the plate member 31. Therefore, the plate-like member 31 and the cylindrical member 32 are positioned below the liquid surface of the molten metal (i.e., in the molten metal) in a state where the liquid surface of the molten metal stored in the crucible 20 and the height of the outlet 21 are substantially equal to each other.

As a result, a "shallow portion" in which the depth of the molten metal having the bottom surface at the upper surface (horizontal surface) of the plate-like member 31 is small is formed in the molten metal stored in the crucible 20 so as to be continuous in the horizontal direction from the upper end portion of the cylindrical member 32 (therefore, the inner peripheral edge of the plate-like member 31).

When the stirring rod 33 (therefore, the screw 33a) is rotated in the predetermined first rotational direction by the motor M1, a swirling upward flow is generated in the molten metal located inside the cylindrical member 32 as described above.

When the swirling upward flow is generated, the molten metal located at the lower portion in the crucible 20 is introduced into the cylindrical member 32 through the inlet 32a at the lower end portion of the cylindrical member 32. The molten metal introduced into the tubular member 32 rises while swirling inside the tubular member 32, and is discharged from the upper end portion of the tubular member 32 while swirling.

The molten metal discharged from the upper end portion of the cylindrical member 32 while swirling moves to the "shoal portion", and then spreads toward the outer peripheral edge of the plate-like member 31 (therefore, the inner wall surface of the crucible 20) while swirling in the horizontal plane. The molten metal reaching the outer peripheral edge of the plate-like member 31 passes through the annular gap Z, then descends along the inner wall surface of the crucible 20, and returns to the lower portion in the crucible 20. The molten metal returned to the lower portion in the crucible 20 is introduced into the cylindrical member 32 again from the lower end portion of the cylindrical member 32. As a result, the molten metal stored in the crucible 20 is uniformly circulated as a whole.

The temperature of the molten metal circulating in the crucible 20 is maintained and adjusted to an appropriate high temperature by adjusting the heating power of the burner 41. The fan 42 is driven to rotate in a predetermined second rotational direction by the motor M2. Thereby, the gas in the upper space S2 is introduced toward the combustion chamber S1.

The amount of the metal material charged into the crucible 20 is adjusted by controlling the rotation angle of the impeller 52 of the charging chute 51. In the present embodiment, the metal material is charged into the "shoal portion" through the outlet portion 51b of the charging chute 51.

In the present embodiment, a "bulk metal material in an undried state, such as a compact obtained by compressing and solidifying a metal powder such as an aluminum cutting powder, that is, a material molded to a size such that the bulk metal material is not impregnated when put into a" shoal portion "is" put into the "shoal portion". In other words, the height difference between the plate-like member 31 and the outlet 21 is set so as not to exceed the initial size of the bulk metal material. The reason why the metal material in a lump is charged is that the surface area can be reduced as compared with a metal material in a powder form and oxidation is difficult.

When such a bulk metal material is put into the "shoal portion", the bulk metal material moves along the flow of the molten metal swirling in the horizontal plane in the "shoal portion" while being melted by the molten metal and gradually reduced in volume in a state where the upper portion thereof is exposed from the molten metal surface of the molten metal. In this process, soot and water vapor from oil and water such as cutting oil attached to the metal material are released from the portion of the bulk metal material exposed from the molten metal. Therefore, the drying process is not performed before the bulk metal material is charged, and the oil moisture can be safely removed from the bulk metal material.

The bulk metal material, which has been reduced in volume and moved in the "shoal portion", reaches the annular gap Z shortly after the bulk metal material is reduced in volume until the bulk metal material can pass through the annular gap Z and remain in the vicinity of the annular gap Z. That is, the width of the annular gap Z is set not to exceed the initial size of the bulk metal material. When the volume is reduced to a size that can pass through the annular gap Z, the bulk metal material passes through the annular gap Z and then descends along the inner wall surface of the crucible 20 along the flow of the molten metal circulating in the crucible 20. The descending bulk metal material is completely melted in the lower portion of the crucible 20, becomes a part of the molten metal, is introduced into the cylindrical member 32 from the lower end portion of the cylindrical member 32, and circulates in the crucible 20.

As described above, the soot generated from the bulk metal material is discharged to the upper space S2. The soot discharged to the upper space S2 is introduced into the combustion chamber S1 through the passage 17 by the rotation of the fan 42. The soot introduced into the combustion chamber S1 is combusted (post-combustion) in the combustor 41 in the same manner as the fuel gas. Therefore, the soot can be reused as fuel for the burner 41, and thus energy efficiency is increased.

The exhaust gas generated by the combustion in the combustion chamber S1 is discharged to the outside through the exhaust passage 14. Then, the secondary air at normal temperature is introduced into the exhaust passage 14 through the passage 15. The purpose of introducing the secondary air at normal temperature into the exhaust passage 14 is to prevent harmful substances such as dioxin, which can be generated by the combustion of the soot described above, from being released to the outside by rapidly cooling the temperature of the exhaust gas.

As described above, the metal material waiting at the position of the impeller 52 is also located in the middle of the passage 17. Therefore, the metal material on standby is exposed to the high-temperature oil smoke passing through the passage 17. As a result, the metal material on standby can be subjected to preliminary drying treatment at a point before the metal material is charged into the molten metal.

(action/Effect)

As described above, according to the present embodiment, since the crucible 20 is heated by the heat of the burner 41, the inside of the crucible 20 functions as a "temperature increasing chamber". Since the molten metal stored in the crucible 20 is stirred by the screw 33a of the stirring rod 33, the inside of the crucible 20 also functions as a "melting chamber". That is, the interior of the single crucible 20 can be used as a "heating chamber" and a "melting chamber". Therefore, the entire apparatus can be made compact as compared with the apparatus described in the document of the background art in which the "temperature increasing chamber" and the "melting chamber" are separately provided.

Further, according to the present embodiment, the bulk metal material charged into the shoal portion moves in the shoal portion along the flow of the molten metal swirling in the horizontal plane while being melted by the molten metal and gradually reduced in volume in a state where the upper portion thereof is exposed from the molten metal surface of the molten metal. In this process, soot and water vapor from oil and water such as cutting oil adhering to the metal material can be released from the portion of the bulk metal material exposed from the molten metal. Therefore, the oil and water can be safely removed from the bulk metal material without performing a drying process before the bulk metal material is charged.

Further, according to the present embodiment, soot derived from oil components contained in the metal material can be guided to the combustion chamber S1, and the soot guided to the combustion chamber S1 can be combusted (post-combustion) in the combustor 41 in the same manner as the fuel gas. Therefore, the soot can be reused as fuel for the burner 41, and thus energy efficiency is improved. In addition, the oil smoke can be completely combusted to be harmless.

Further, according to the present embodiment, the metal material waiting at the position of the impeller 52 of the input chute 51 is located in the middle of the passage 17 through which the high-temperature soot moves from the upper space S2 to the combustion chamber S1. Therefore, the metal material waiting at the position of the impeller 52 can be subjected to preliminary drying treatment at a time before being put into use.

The present invention is not limited to the above-described exemplary embodiments, and various applications and modifications can be made without departing from the object of the present invention. For example, the following embodiments to which the above embodiments are applied may be implemented.

In the above embodiment, as the metal material to be charged, a non-ferrous metal bulk material such as an aluminum compact can be used, but an iron bulk material such as an iron compact can also be used. As the metal material to be charged, a non-ferrous metal or an iron cutting powder material may be used. In the case of using the cutting powder material as the charged metal material, the entire cutting powder material can be immersed in the molten metal immediately after charging the molten metal, and therefore it is preferable to use the cutting powder material subjected to the drying treatment.

In the above embodiment, the plate-like member 31 is provided to form the "shoal portion", but the "shoal portion" may not be formed. In this case, even when a lump material such as a briquette is used as the metal material to be charged, the lump material is preferably used after being dried because the lump material can be entirely immersed in the molten metal immediately after being charged in the molten metal.

In the above embodiment, the annular gap Z is formed between the outer peripheral edge of the plate-like member 31 and the inner wall surface of the crucible 20, but a gap that is not annular (i.e., discontinuous over the entire circumference in the circumferential direction) may be formed.

In the above embodiment, the furnace body 10 for accommodating the crucible 20 is provided, but the furnace body 10 may not be provided. That is, the entire crucible 20 may be exposed to the outside. In this case, a burner is placed near the outer wall of the crucible 20, and the crucible 20 can be heated by the burner. The exhaust gas generated by the combustion of the burner is directly discharged to the outside.

Description of the reference symbols

10 … furnace body, 11 … bottom wall, 12 … side wall, 13 … upper wall, 20 … crucible, 30 … stirring part, 31 … plate-shaped member, 32 … cylindrical member, 33 … stirring rod, 33a … screw, 40 … heating part, 41 … burner, 42 … fan, 50 … input part, 51 … input chute, 52 … impeller, M1, M2 … motor.

Claims

1. A metal melting apparatus includes:

a crucible (20) having an open upper portion and containing molten metal for melting a metal material therein;

a stirring section (30) that stirs the molten metal stored inside the crucible (20) and generates a flow of the molten metal inside the crucible (20); and

a heating unit (40) that heats the crucible (20),

the stirring section (30) is provided with:

a cylindrical member (32) which is disposed in the vertical direction in the molten metal stored in the crucible (20) at the center of the crucible (20) when the crucible (20) is viewed from above;

a swirling upward flow generating unit (33, M1) that generates a swirling upward flow in which the molten metal located inside the cylindrical member (32) rises while swirling; and

a plate-like member (31) connected to the upper end of the cylindrical member (32) and arranged in the horizontal direction in the molten metal stored in the crucible (20),

a gap is formed between the outer edge of the plate-shaped member (31) and the inner wall surface of the crucible (20),

a shoal portion having a small depth of molten metal with the upper surface of the plate-like member as a bottom surface is formed continuously in a horizontal direction from an upper end portion of the cylindrical member, and the metal material is fed into the shoal portion.

2. The metal melting apparatus of claim 1,

the metal melting apparatus is provided with a furnace body (10) which accommodates the crucible (20) therein,

the heating unit (40) includes:

a burner (41) that heats the crucible (20) by burning a fuel gas in a combustion chamber (S1) defined by the outer wall of the crucible (20) and the side wall (12) and the bottom wall (11) of the furnace body (10); and

and a soot introduction unit (42, M2, 17) for guiding soot originating from oil components contained in the metal material, which is released into an upper space (S2) defined by the opening of the crucible (20) and the upper wall (13) of the furnace body (10), to the combustion chamber (S1).

3. The metal melting apparatus of claim 2,

the metal melting device is provided with a feeding part (50) for feeding the metal material to the molten metal accumulated in the crucible (20),

the input unit (50) is configured such that the metal material on standby in the input unit (50) is positioned in the middle of a path through which the soot is moved from the upper space (S2) to the combustion chamber (S1) by the soot introduction unit (42, M2, 17).