JP4362712B2 - Crucible melting and holding furnace - Google Patents

Description

  The present invention relates to a preheating tower for charging a material to be melted and preheating, a crucible type melting crucible chamber using a crucible, and a continuous melting type crucible melting and holding furnace including a holding crucible chamber as constituent elements. In this specification, the material to be melted includes non-ferrous metal ingots such as aluminum, zinc, and copper alloys, their return materials, chips, empty cans, scrap materials, and those that are pressed and pressed, etc., Or it is used to include non-ferrous metal materials with parts such as iron, rubber, and plastic.

  As shown in FIG. 4, this type of crucible melting and holding furnace includes a preheating tower 100 of a material to be melted a, a melting crucible furnace 101 installed immediately below the preheating tower 100, and a holding furnace juxtaposed in the crucible furnace 101. A crucible furnace 102 is provided. The melting crucible furnace 101 includes a melting crucible 103, a melting crucible chamber 104, and a burner 105. The holding crucible furnace 102 includes a holding crucible 107, a holding crucible chamber 106, and a burner 105A. Then, the material to be melted a to be supplied from the preheating tower 100 to the melting crucible furnace 102 is melted by the burner 105, and the molten molten metal continuously overflows toward the holding crucible 107 by the rod 108 of the melting crucible 103. In the crucible 107, the molten metal is pumped out after being heated up to a target casting temperature by a burner (see, for example, Patent Document 1).

  Combustion exhaust gas generated in the melting crucible chamber 104 rises in the gap 109 between the melting crucible chamber 104 and the melting crucible 103 and is supplied to the preheating tower 100 as a preheating source, while the holding crucible chamber. Combustion exhaust gas generated in 106 rises through the gap 110 between the holding crucible chamber 106 and the holding crucible 107 and flows into the melting crucible chamber 104 and the preheating tower 100 from the exhaust gas flow path 111 and dissolves. The combustion exhaust gas generated in the crucible chamber 104 is joined. And since the to-be-melted material a preheated in the preheating tower 100 falls continuously in the preheating tower 100 and is melted in the molten metal of the crucible 103, the temperature of the molten metal is always low (close to the melting point of the to-be-melted material). Temperature).

  The instruction to input the material to be melted a into the preheating tower 100 is performed by sensing the temperature of the combustion exhaust gas after the heat exchange passing through the exhaust hole 113 of the opening / closing lid 112 at the top of the preheating tower 100 with the thermocouple 114. If the amount of the material to be melted a in the preheating tower 100 decreases, the exhaust gas temperature after heat exchange rises. When the temperature of the combustion exhaust gas exceeds the set range, the thermocouple 114 detects this and gives a charging instruction. Then, the opening / closing lid 112 is opened, and the heating of the melting crucible chamber 104 by the burner 105 is stopped. When the additional charging of the material to be melted a is completed, the opening / closing lid 112 is closed and heating by the burner 105 is resumed.

  Such a crucible type melting and holding furnace heats all the combustion exhaust gas generated from both the melting crucible chamber 104 and the holding crucible chamber 106 with the melted material a and uses it for preheating the melted material a. There are advantages in that energy saving is achieved and generation of oxides is reduced.

  However, when the capacity of the holding crucible 107 is large or the melting point of the material to be melted a is high, the melting temperature and the holding temperature are increased, a large amount of combustion exhaust gas is generated, and the temperature of the combustion exhaust gas is increased. The material to be melted a can be sufficiently preheated only by heat exchange of the combustion exhaust gas generated in the melting crucible chamber 103. Therefore, when all the high-temperature combustion exhaust gas generated from both chambers is used as the preheating of the material to be melted a, the temperature of the preheating tower 100 is increased, so that the material to be melted a is sufficiently filled in the preheating tower 100. Even in such a state, the exhaust gas temperature after heat exchange often exceeds the set temperature for exhaust gas detection, and as a result, the input instruction is frequently performed, causing overcharge of the material to be melted a. It interferes with the input management of the melting material a.

Although it is conceivable to avoid overcharge of the material by setting the sensing temperature of the exhaust gas after heat exchange to a high temperature, the heat exchange rate between the hot exhaust gas formed by joining and the material to be melted a decreases. Effective use cannot be achieved and the energy saving effect will be impaired.
JP 2000-130948 A

  The present invention has been made in view of the above points, and even if the detection temperature of the exhaust gas after heat exchange is not set to a high temperature, it is possible to prevent over-jersey of the material to be melted, and to effectively exhaust the exhaust gas. A crucible melting and holding furnace that can be used is provided.

The crucible melting and holding furnace of the present invention includes a preheating tower for preheating a material to be melted, a melting crucible installed below the preheating tower and receiving the material to be melted from the preheating tower, and the melting A melting crucible chamber for housing the melting crucible; a melting heating means for heating the melting crucible; a holding crucible for receiving a supply of molten metal from the melting crucible; and a holding crucible chamber for accommodating the holding crucible And a holding heating means for heating the holding crucible, the melting crucible chamber and the holding crucible chamber are adjacent to each other via a common side wall, and the holding crucible is And the interior is partitioned into a hot water receiving chamber and a pumping chamber by a partition, and the hot water receiving chamber and the pumping chamber communicate with each other below the partition, and are connected to an opening formed in the shared side wall. A draining hot water covering the upper side of the hot water reception room And a transfer part that supplies the molten metal from the melting crucible to the hot water receiving chamber of the holding crucible through the opening and the hot water hood, and the partition part is formed from the tip of the hot water hood. The holding crucible chamber is formed between the holding crucible chamber and the holding crucible chamber by closing a gap between the holding crucible chamber and the opening of the holding crucible with a partition. The combustion chamber is sealed to prevent high temperature exhaust gas generated by the holding heating means from flowing into the melting crucible chamber and the preheating tower.

  Further, it is desirable that the holding heating means is a regenerative burner, and the regenerative burner is attached to an opening formed in a wall portion of the holding crucible chamber.

  Further, it is desirable that the holding heating means is an electric heater, and the electric heater is disposed on the inner wall surface of the holding crucible chamber.

  Further, it is desirable that the holding crucible is an iron crucible, an outer casing is projected from the mouth of the crucible, and the outer casing is used as the partition body.

  According to the crucible type melting and holding furnace of the present invention, the high temperature exhaust gas generated by the holding heating means is prevented from flowing into the melting crucible chamber and the preheating tower. Only the heated gas can be used for preheating the material to be melted. Therefore, it is possible to prevent the material to be melted from being overcharged when a large-capacity holding crucible is used or when the material to be melted has a high melting point, and it becomes easy to manage the material to be melted.

  In addition, a gap between the holding crucible chamber and the opening of the holding crucible is closed with a partition body, and the combustion chamber formed between the holding crucible and the holding crucible chamber is made to have a sealed structure. Thus, if the high temperature exhaust gas is prevented from flowing into the melting crucible chamber and the preheating tower, the high temperature exhaust gas generated by the holding heating means flows into the melting crucible chamber and the preheating tower. Can be easily prevented.

  In addition, if the combustion chamber has a sealed structure and the holding heating means is a regenerative burner, the exhaust gas temperature can be lowered by sufficiently exchanging heat between the high-temperature combustion exhaust gas and air, thus enabling energy saving. In addition, overmelting of the material to be melted can be eliminated and the material to be melted can be sufficiently preheated.

  Further, if the combustion chamber has a sealed structure and the holding heating means is an electric heater, it can be held and heated with high electric heating efficiency, so that energy saving can be achieved, and the overcharge of the melted material is eliminated and the covering is eliminated. The melting material can be sufficiently preheated.

  Further, the molten metal overflowing from the melting crucible is continuously transferred to the holding crucible, and the molten metal flowing in the holding transfer crucible is supplied with hot air from the molten metal in the holding crucible and the melting crucible chamber. If the flow path for making the high temperature exhaust gas from contact is provided, the temperature fall of the molten metal which flows through a transfer part can be prevented, and solidification of a molten metal can be prevented.

  Embodiments of a crucible melting and holding furnace of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1
FIG. 1 schematically shows the entire crucible melting and holding furnace of the present embodiment. The melting and holding furnace A is installed in a preheating tower 1 of a material to be melted a such as an aluminum ingot, and immediately below the preheating tower 1. The melting crucible furnace 2 is provided, and the holding crucible furnace 3 juxtaposed to the melting crucible furnace 2 is provided.

  The melting crucible furnace 2 includes a melting crucible chamber 4, a furnace lid 41 of the melting crucible chamber 4, a melting crucible 6 installed in the melting crucible chamber 4 via a crucible base 5, and a melting crucible 6 And a peripheral space 7 is formed between the crucible 6, the melting crucible chamber 4 and the furnace lid 41. The peripheral space 7 is a burner as indicated by an arrow. It becomes an ascending passage through which the B combustion exhaust gas (hot gas) flows.

  The holding crucible furnace 3 includes a holding crucible chamber 8, a furnace lid 81 of the holding crucible chamber 8, a holding crucible 10 installed in the holding crucible chamber 8 via a crucible base 9, and a holding crucible 10 A self-type regenerative burner (heating means for holding) RB. An opening 8a is formed in the wall of the holding crucible chamber 8, and a regenerative burner RB is attached to the opening 8a.

The furnace lid 81 also serves as a partition that closes the gap 82 formed between the holding crucible chamber 8 and the opening of the holding crucible 10, and thereby, between the holding crucible chamber 8 and the holding crucible 10. The formed combustion chamber 83 has a sealed structure and prevents high-temperature combustion exhaust gas from flowing into the melting crucible chamber 4 and the preheating tower 1. The melting crucible chamber 4 and the holding crucible chamber 8 include a heat insulating material such as A lining is applied with a ceramic heat insulating material, and a common side wall 13 is provided at the boundary portion.

  The regenerative burner RB is a burner that recovers combustion exhaust gas and improves the thermal efficiency of the furnace.

  In order to enable heating from the bottom of the crucibles 6, 10, the crucible bases 5, 9 have a cylindrical shape and are provided with combustion gas flow grooves 5 a, 9 a on the sides.

  The holding crucible 10 is partitioned into a hot water receiving chamber 19 and a pumping chamber 20 by a partition portion 18, and both chambers 19, 20 communicate with each other via a communication port 21 below the partition portion 18. 6 is configured to receive molten metal 17 from 6.

  The melting crucible 6 and the holding crucible 10 are connected via an overflow-type discharge port 15 provided in the body of the melting crucible 6 and a bowl-shaped transfer unit 16 connected to the discharge port 15. 17 can be continuously transferred from the melting crucible 6 into the holding crucible 10 via the transfer unit 16 while overflowing the discharge port 15. The transfer part 16 extends through the opening 14 a formed in the shared side wall 13 to a position above the liquid level of the molten metal in the hot water receiving chamber 19 of the holding crucible 10. The transfer unit 16 is not limited to a bowl shape, and may be a pipe shape, for example.

  The continuous transfer of the molten metal 17 is performed by utilizing the head difference between the liquid levels in the crucibles 6 and 10. The formation position of the discharge port 15 with respect to the body portion of the melting crucible 6 may be selected and determined in consideration of the amount of the molten metal 17 that stays in the crucible 6 and the liquid level.

  As the melting and holding crucibles 6 and 10, graphite crucibles are suitable, but iron crucibles (cast iron, ordinary steel, special steel, etc.) can be used as necessary.

  The upper side of the hot water receiving chamber 19 in the holding crucible 10 is covered with a hot water hood 14 b, and a flow path 14 is formed around the transfer section 16 by the hot water hood 14 b and the opening 14 a of the shared side wall 13. Then, the hot air of the molten metal in the holding crucible 10 is guided to the hot water outlet 16a of the transfer unit 16 by the flow path 14, so that the molten metal flowing through the transfer unit 16 is exposed to the hot air of the molten metal and is heated and transferred. The temperature drop of the molten metal 17 inside is prevented.

  The molten metal 17 overflowing into the holding crucible chamber 8 is raised to the operating temperature and is cast from the pumping chamber 20. Further, in the hot water receiving chamber 19, various types of molten metal treatment, removal of oxides accumulated on the molten metal surface, and the like are appropriately performed as necessary.

  The molten metal 17 may leak from the crucibles 6 and 10 through cracks and the like, and in order to discharge the leaked molten metal to the outside of the furnace, for example, the lower end of the shared side wall 13 and the lower end of the side wall of the holding crucible chamber 8 are not shown. A drain outlet is formed.

   The melting crucible chamber 4 of the melting crucible furnace 2 has an uncovered bottomed cylindrical shape, and a cylindrical preheating tower 1 is installed in a two-stage stacked state and concentrically via an upper furnace lid 41. . The lower end of the furnace lid 41 opens above the upper end of the melting crucible 6 and opens into the crucible 6, so that the material to be melted a can be put into the crucible 6 through the preheating tower 1.

 The upper end side of the gap 7 in the melting crucible chamber 4 is communicated with the preheating tower 1 via an annular gap 24 between the upper end of the melting crucible 6 and the lower end of the hanging wall 41A formed in the furnace lid 41. The combustion exhaust gas can be supplied into the preheating tower 1 as a preheating source. Since the combustion exhaust gas once flows downward by the hanging wall 41A as shown by the arrow, the material to be melted a before being immersed in the molten metal located in the melting crucible 6 can also be preheated.

  At the upper end of the preheating tower 1, there is an inlet 27 for the material to be dissolved a. The inlet 27 is provided with an opening / closing lid 28, and the opening / closing lid 28 is provided with an exhaust port 29 for combustion exhaust gas. A thermocouple 25 for sensing the temperature of the combustion exhaust gas after the heat exchange passing through the exhaust hole is attached to the open / close lid 28. The formation of the exhaust port 29 is necessary in order to guide the combustion exhaust gas as an updraft from the circumference 7 through the annular gap 24 into the preheating tower 1 by the draft effect. The opening / closing lid 28 can be opened / closed by an automatic opening / closing mechanism equipped with a driving device.

 In order to replace the melting crucible 6 or pump out the remaining hot water in the crucible 6, the preheating tower 1 can be appropriately moved from the two-tiered position shown in FIG. 1. The total weight of the preheating tower 1 is supported by a carriage 30, and the carriage 30 can run on a guide rail 31 supported and fixed to the melting crucible chamber 4. The second position where the two-stage stack is unwound from the first position where the tower 1 is overlapped with the furnace cover 4A of the melting crucible chamber 4, that is, the position where the upper end opening of the melting crucible chamber 4 can be made completely free. Up to this point, the structure can be slid. In order to stop the cart 30 at the first position and the second position, various position restricting means can be employed.

  FIG. 1 shows the situation during normal operation of the melting and holding furnace. The combustion gas supplied from the bottom of the melting crucible chamber 4 to the inside of the melting crucible chamber 6 rises in the circumferential space 7 while heating the melting crucible 6 and becomes combustion exhaust gas. The combustion exhaust gas enters the preheating tower 1 from the upper end of the circumferential space 7 through the annular gap 24 communicating therewith, and exchanges heat with an ingot or the like a in the preheating tower 1 and is effectively used as a preheating source. Is discharged to the outside of the furnace through the exhaust port 29. The temperature of the flue gas discharged from the furnace is reduced to, for example, 375 ° C. or less by heat exchange with the material to be melted a. This temperature reduction of the combustion exhaust gas leads to improvement of the working environment. On the other hand, since the holding crucible chamber 8 has a sealed structure as described above, the high-temperature combustion exhaust gas in the holding crucible chamber 8 flows into the preheating tower 1 and the melting crucible chamber 4 and merges with the combustion exhaust gas from the burner B. Never do.

  The material to be melted a is melted in order from the lower end portion immersed in the molten metal 17 of the melting crucible 6. The material to be melted a falls under its own weight as the melting progresses, soaks in the molten metal, and is always melted in the molten metal 17, so that the temperature of the molten metal 17 is kept substantially constant at a low temperature near the melting point of aluminum.

  The molten metal 17 in the melting crucible 6 is continuously transferred to the hot water receiving chamber 19 of the holding crucible 10 through the transfer unit 16 while overflowing the discharge port 15 due to the head difference, and can be continuously melted and held. become.

  The low-temperature molten metal 17 that has flowed into the hot water receiving chamber 19 of the holding crucible 10 is heated and held to a required temperature by pouring the combustion gas and poured. Various molten metal treatments and oxide removal are performed in the hot water receiving chamber 19 as necessary. The molten metal 17 in the hot water receiving chamber 19 flows into the pumping chamber 20 through the communication port 21 at the lower end of the partition plate 18 to prepare for pumping use.

  The instruction to input the material to be melted a into the preheating tower 1 is performed by detecting the temperature of the combustion exhaust gas after the heat exchange passing through the exhaust hole of the opening / closing lid 28 with the thermocouple 25 as described above. If the amount of the material to be melted a decreases, the exhaust gas temperature after heat exchange rises. If the temperature of the combustion exhaust gas exceeds the set range, the thermocouple 25 senses this and gives an input instruction to open / close the lid 28. And the heating of the melting crucible chamber 4 by the burner B is stopped. When the additional charging of the material to be melted a is completed, the opening / closing lid 28 is closed and heating by the burner B is resumed.

  The exhaust gas temperature after the heat exchange varies depending on the melting point of the material to be melted a and the amount of the material to be melted a that is filled in the preheating tower 1. It is set in the range of 300 to 500 ° C.

  Thus, the crucible type melting and holding furnace has a structure comprising the preheating tower 1 and the crucible furnaces 2 and 3 divided into two for melting and holding, and from the melting crucible furnace 2 to the holding crucible furnace 3. Since the hot water is continuously transferred to the inside and the molten metal is pumped out from the holding crucible furnace side, the preheating tower 1 is melted by placing it above the upper end opening of the melting crucible furnace 2. Only the combustion exhaust gas generated in the crucible furnace 2 can be used for preheating in the preheating tower 1.

  Furthermore, since the furnace walls of the crucible furnaces 2 and 3 do not come into contact with the molten metal, it is possible to apply a lining with a ceramic fiber heat insulating material. Ceramic heat insulating materials are light weight materials, so there is little heat storage, and the amount of heat released from the furnace wall is reduced, saving energy.

Embodiment 2
In the crucible type melting and holding furnace shown in FIG. 2, an electric heater H is disposed in the holding crucible furnace 3 in place of the regenerative burner RB. The electric heater H is disposed on the inner wall surface of the holding crucible chamber 8 and heats the holding crucible 10 by the heat generated by the heating wire. In addition, about the part which is the same as that of 1st Embodiment, or a similar part, the code | symbol same as the code | symbol attached | subjected to 1st Embodiment is attached | subjected to FIG. 2, and description of the part is abbreviate | omitted.

  As in the first embodiment, the combustion chamber 83 of the holding crucible furnace 3 has a sealed structure by the furnace lid 81, so that the heating loss due to the electric heater H is reduced and the electrothermal efficiency can be improved.

  FIG. 3 shows an embodiment in which the holding crucible 10 is an iron crucible, an outer casing 10A that also serves as a furnace lid 81 is projected from the mouth of the crucible 10, and the gap 82 is closed with the outer casing 10A.

It is a front sectional view showing the crucible type melting and holding furnace of Embodiment 1 of the present invention. It is front sectional drawing which shows the crucible type | mold melting holding furnace of Embodiment 2 of this invention. It is a front sectional view showing a part of a crucible type melting and holding furnace of another embodiment of the present invention. It is a front sectional view of the conventional crucible type melting and holding furnace.

Explanation of symbols

1 Preheating tower 2 Melting crucible furnace 3 Holding crucible furnace 4 Melting crucible chamber B Burner (heating means for melting)
RB regenerative burner (heating means for holding)
H Electric heater (heating means for holding)
8 Holding crucible chamber 10 Holding crucible

Claims (4)

A preheating tower for preheating the material to be melted, a melting crucible installed below the preheating tower and receiving the material to be melted from the preheating tower, and a melting crucible chamber for housing the melting crucible A melting heating means for heating the melting crucible, a holding crucible for receiving a supply of molten metal from the melting crucible, a holding crucible chamber for housing the holding crucible, and a holding for heating the holding crucible A melting and holding furnace comprising:
The melting crucible chamber and the holding crucible chamber are adjacent to each other via a shared side wall,
The holding crucible is partitioned into a hot water receiving chamber and a pumping chamber by a partition part, and the hot water receiving chamber and the pumping chamber communicate with each other below the partition part,
A hot water hood connected to an opening formed in the shared side wall and covering the upper side of the hot water receiving chamber, and a molten metal from the melting crucible to the hot water receiving chamber of the holding crucible through the opening and the hot water hood And a transfer section for supplying
The partition is provided so as to extend downward from the tip of the hot water hood,
By closing the gap between the holding crucible chamber and the opening of the holding crucible with a partition, and forming a combustion chamber formed between the holding crucible and the holding crucible chamber with a sealed structure , crucible type melting and holding furnace wherein the hot exhaust gas caused by the holding heating means is configured to prevent the flow into the melting crucible chamber and the preheating tower. The crucible melting and holding furnace according to claim 1 , wherein the holding heating means is a regenerative burner. The crucible type melting and holding furnace according to claim 1 , wherein the holding heating means is an electric heater, and the electric heater is disposed on an inner wall surface of the holding crucible chamber. The crucible type according to any one of claims 1 to 3 , wherein the holding crucible is an iron crucible, and an outer casing protrudes from a mouth portion of the crucible, and the outer casing is used as the partition body. Melting and holding furnace.

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