Molten metal-holding furnace

Abstract

To efficiently heat and maintain temperature of a molten metal, and to prevent an oxide from adhering to a molten metal-heating element and prevent hydrogen gas bubbles from being released into the molten metal.SOLUTION: A molten metal-holding furnace has: a holding chamber 13 for holding a molten metal MM; and a strip-shaped molten metal-heating element 2 that extends diagonally downwards from a side wall 13Ds to heat the molten metal MM. The bottom of the holding chamber 13 located below the molten metal-heating element 2 has a sloping floor surface 13Db1 that slopes in the same direction as the molten metal-heating element 2. The molten metal MM in an easy-heating space Y between the molten metal-heating element 2 and the sloping floor surface 13Db1 comes into contact with a surface of the molten metal-heating element 2, thereby heat is transferred to the molten metal MM. A lower limit liquid surface level of the molten metal MM is set at a height equal to or higher than an upper end 2G of the molten metal-heating element 2 inside the holding chamber 13. The molten metal MM is replenished before the height of the liquid surface of the molten metal MM inside the holding chamber 13 falls below the lower limit liquid surface level, and the height of the liquid surface of the molten metal MM inside the holding chamber 13 is maintained at a height equal to or higher than an upper end 2G of the molten metal-heating element 2.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a molten metal holding furnace for holding a molten metal obtained by melting a non-ferrous metal such as aluminum or an aluminum alloy. [Background technology]

[0002] There are various shapes of molten metal holding furnaces that hold molten metal to be supplied to casting equipment such as die casting machines.

[0003] For example, the two-chamber type molten metal holding furnace for low-pressure casting disclosed in the following Patent Document 1 is a two-chamber type furnace that is equipped with a lift-up shutoff valve that opens and closes a molten metal flow passage port that connects a molten metal holding chamber and a pressurizing chamber, the pressurizing chamber has a pressurizing section and a molten metal outlet port that communicate with each other at their bottoms, and tube heaters are disposed in the molten metal holding chamber and the pressurizing chamber, the molten metal in the molten metal holding chamber is introduced up to a constant liquid level in the pressurizing section when the molten metal flow passage port is open, and then, when the molten metal flow passage port is closed, pressure is applied to the liquid level in the pressurizing section by a pressurized gas, so that the molten metal in the outlet port is filled into a cavity of a mold. In this low-pressure casting molten metal holding furnace, the inner wall surfaces of the pressurizing section and the discharge section are constructed of lining members made of a cylindrical integral sintered product made of fine ceramics, and the lower end of the lining member for the pressurizing section is positioned below the liquid level when the molten metal is completely filled into the cavity, while the upper end of the lining member for the discharge section is positioned above the upper limit liquid level of the molten metal holding chamber and its lower end is positioned below the liquid level when the pressure in the pressurizing section is released, and the constant liquid level of the pressurizing section is set to the lower limit liquid level of the molten metal holding chamber.

[0004] In this two-chamber type low-pressure casting molten metal holding furnace, the inner wall surfaces of the pressure applying section and the tapping section are constructed with lining members made of a cylindrical integral sintered product of fine ceramics, and the lower ends of the lining members of the pressure applying section and the tapping section are positioned lower than the minimum liquid level in each section. This means that cracks and damage to the inner wall surfaces due to penetration of molten metal into the inner wall surfaces of the pressure applying section and the tapping section can be reliably prevented for a long period of time, thereby ensuring stable long-term operability and enabling the production of good casting products. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4519806 Summary of the Invention [Problem to be solved by the invention]

[0006] Prior Art Document 1 discloses that two tube heaters are provided on the side wall of the molten metal holding chamber, but does not disclose any specific method for installing the tube heaters.

[0007] Furthermore, for example, in the case of a holding chamber for holding the molten metal of a molten metal holding furnace, the amorphous refractory forming the holding chamber container in which the molten metal is actually held and the insulating layer located outside the holding chamber container contain moisture from the atmosphere when they are made, and even if they are dried, the moisture is not completely removed. The moisture that is not completely removed from the amorphous refractory forming the holding chamber container reacts with the molten metal and is taken into the molten metal in the form of hydrogen atoms, and is released into the molten metal as hydrogen gas bubbles. The moisture that is not completely removed from the insulating layer located outside the holding chamber container reacts with the molten metal through the amorphous refractory forming the holding chamber container and is taken into the molten metal in the form of hydrogen atoms, and is released into the molten metal as hydrogen gas bubbles. These hydrogen gas bubbles may cause pinholes in the cast product. At present, hydrogen gas bubbles are removed by a degassing device using an inert gas (nitrogen, argon, etc.), but this is not sufficient, and there is a demand for further suppression of the release of hydrogen gas bubbles.

[0008] An object of the present invention is to provide a molten metal holding furnace that can efficiently raise and maintain the temperature of molten metal held in the molten metal holding furnace, while suppressing adhesion of oxides to a molten metal heating element that heats the molten metal and suppressing the release of hydrogen gas bubbles into the molten metal. [Means for solving the problem]

[0009] The aspects of the means for solving the above problems are as follows.

[0010] (First aspect) a holding chamber for holding the molten metal; a slender molten metal heating body extending obliquely downward from a side wall portion of the holding chamber and heating the molten metal inside the holding chamber; a bottom surface of the holding chamber located below the molten metal heating body has an inclined floor surface that is inclined in the same direction as the molten metal heating body while being spaced apart from the molten metal heating body by a predetermined distance; A space that is easily heated is formed between the molten metal heater and the inclined bed surface, The molten metal in the easily-heating space is in contact with a surface of the molten metal heater, so that heat from the molten metal heater is transferred to the molten metal, a lower limit liquid level of the molten metal in the holding chamber is set to a height equal to or higher than an upper end of the molten metal heater provided in the holding chamber, The molten metal is replenished into the holding chamber before the height of the liquid surface of the molten metal (hereinafter referred to as the "liquid surface level") in the holding chamber falls below the lower limit liquid surface level, and the height of the liquid surface of the molten metal in the holding chamber is maintained at a height equal to or higher than the upper end of the molten metal heater. A molten metal holding furnace characterized by:

[0011] (Action and effect) According to the first aspect of the molten metal holding furnace, in the easily-heatable space formed between the molten metal heating body and the inclined floor surface of the holding chamber, the efficiency of thermal conduction from the entire molten metal heating body to the molten metal can be increased, and the molten metal in the holding chamber can be efficiently heated.

[0012] In addition, in the conventional holding chambers of a substantially cubic or rectangular parallelepiped shape in which the molten metal heater is placed vertically, the height of the holding chamber must be increased to a certain extent in order to accommodate the molten metal heater in the holding chamber. However, when the height of the holding chamber is increased, when the molten metal holding furnace and the existing equipment (for example, the molten metal supply equipment of a die casting machine, which has a maximum height of about 1200 mm; the same applies below) are installed side by side, the height of the molten metal holding furnace is often higher than that of the existing equipment. When a difference in height occurs between the molten metal holding furnace and the existing equipment, the labor required to move the molten metal from the molten metal holding furnace to the existing equipment is large, and the operating efficiency is poor. In addition, when the conventional molten metal heater is placed vertically, the entire molten metal heater may not be immersed in the molten metal, so it cannot be said that the molten metal is heated efficiently. In addition, even when the conventional molten metal heater is placed vertically and the entire part to be heated is immersed in the molten metal, it cannot be said that the molten metal is heated efficiently. For example, consider a case where a molten metal heater is immersed in the molten metal in a melting chamber of a specific size, such as an approximately cube or rectangular parallelepiped, and the molten metal is heated by the molten metal heater with a specific output. In this case, the efficiency of heating the molten metal varies depending on how widely the molten metal heater comes into contact with the molten metal. In other words, the greater the surface area of ​​the molten metal heater that comes into contact with the molten metal, the more efficiently the molten metal can be heated. Therefore, even when a conventional molten metal heater is placed vertically and the entire part to be heated is immersed in the molten metal, it cannot necessarily be said that the molten metal is heated efficiently.

[0013] In order to prevent such problems from occurring, it is conceivable to reduce the height of the holding chamber and widen its width to make it have a similar capacity to the previous holding chamber, and to vertically place a short, wide-diameter molten metal heater in the holding chamber (the diameter needs to be made wider to achieve the same heating capacity as the previous molten metal heater). However, such a molten metal heater is a custom-made product, and is therefore significantly more expensive than the previous molten metal heater (about 10 times the price), resulting in a problem of high initial costs.

[0014] On the other hand, in the conventional holding chamber in which the molten metal heater is placed horizontally, the width of the holding chamber must be increased, which inevitably increases the bottom area of ​​the holding chamber and the installation area of ​​the holding chamber. In addition, if the molten metal heater is damaged, the molten metal may enter the molten metal heater from the damaged part, for example, up to the burner unit if the molten metal heater is an immersion burner, or up to the heater box if the molten metal heater is an immersion heater. In addition, if the molten metal heater is damaged, there is a problem in terms of work that the molten metal heater must be replaced after the molten metal heater is drained to a height lower than the height of the molten metal heater.

[0015] In order to solve the above problems, in the first embodiment, the molten metal heater extends obliquely downward from the side wall of the holding chamber. With this structure, the height of the holding chamber can be made lower than that of a conventional holding chamber in which the molten metal heater is placed vertically. As a result, the above-mentioned problem of reduced operating efficiency can be prevented. In addition, the entire molten metal heater can be immersed in the molten metal, and compared to conventional molten metal heaters placed vertically or horizontally, the length can be increased because the molten metal heater extends obliquely downward, so the surface area of ​​the molten metal heater in contact with the molten metal is increased, and the efficiency of heating the molten metal is improved. Furthermore, the formation of oxide adhesion can be prevented. In addition, the bottom area of ​​the holding chamber can be made smaller than that of conventional holding chambers in which the molten metal heater is placed horizontally, so the installation area of ​​the holding chamber can be reduced, and even if the molten metal heater is damaged, there is no risk of the molten metal heater infiltrating the molten metal heater from the damaged area, for example, to the burner unit if the molten metal heater is an immersion burner, or to the heater box if the molten metal heater is an immersion heater. Furthermore, even if damage occurs, the molten metal heater can be replaced without draining the molten metal to a height lower than the placement height of the molten metal heater as in the conventional case. Also, since the holding chamber can be made smaller, as described above, moisture from the monolithic refractory material forming the holding chamber container and the insulating layer located on the outside of the holding chamber container reacts with the molten metal and is taken into the molten metal in the form of hydrogen atoms, and the amount of hydrogen gas released into the molten metal as bubbles is reduced, which inevitably suppresses the release of hydrogen gas bubbles.

[0016] In addition, in the first embodiment, an inclined floor surface is provided that is inclined in the same direction as the molten metal heater while leaving a predetermined gap between the molten metal heater and the inclined floor surface. By providing an inclined floor surface in the holding chamber in this manner, the distance between the molten metal heater and the inclined floor surface is kept constant, and the thermal conduction efficiency of the molten metal present in this gap can be increased.

[0017] Furthermore, for example, if a portion of the molten metal heater is exposed above the surface of the molten metal in the holding chamber, the exposed portion of the molten metal heater will heat the air above the surface of the molten metal, resulting in a problem of reduced heating efficiency by the molten metal heater.

[0018] In this aspect, a lower limit liquid level of the molten metal inside the holding chamber is set at a height equal to or higher than the upper end of the molten metal heating body provided inside the holding chamber, and the molten metal is replenished inside the holding chamber before the liquid level of the molten metal inside the holding chamber falls below the lower limit liquid level, so that the liquid level of the molten metal inside the holding chamber is maintained at a height equal to or higher than the upper end of the molten metal heating body.

[0019] With this configuration, all parts of the molten metal heater in the holding chamber are immersed in the molten metal and this state is maintained, so that the heating efficiency by the molten metal heater can be improved.

[0020] (Second aspect) The molten metal holding furnace of the first aspect, wherein the inclination angle of the molten metal heater and the inclination angle of the inclined floor surface are both within a range of 20 to 45 degrees.

[0021] (Action and effect) By making the molten metal heater and the inclined bed surface approximately parallel, the distance between the surface of the molten metal heater and the inclined bed surface becomes approximately the same at any point, so that heat can be uniformly transferred from the molten metal heater to the molten metal in the easy-to-heat space. As a result, the molten metal can be efficiently heated, and it is possible to prevent a situation in which a part of the molten metal is insufficiently heated and the quality of the molten metal is reduced.

[0022] In addition, by setting the inclination angle of the molten metal heater in the range of 20 to 45 degrees, the height of the molten metal holding furnace can be reduced. If the height of the molten metal holding furnace can be reduced, the difference in height between the molten metal holding furnace and other existing equipment is reduced. As a result, the effort required to move the molten metal from the molten metal holding furnace to the existing equipment is reduced, improving operating efficiency.

[0023] (Third aspect) The molten metal holding furnace of the first aspect, wherein a holding chamber lid is provided to close an upper opening of the holding chamber, and the underside of a portion of the holding chamber lid located above the molten metal heating body is inclined in the same direction as the molten metal heating body while leaving a predetermined gap between the molten metal heating body and the holding chamber lid.

[0024] (Action and effect) According to the third aspect of the molten metal holding furnace, the efficiency of heat transfer from the molten metal heating body to the molten metal in the gap between the molten metal heating body and the holding chamber lid can be increased, and the molten metal in the holding chamber can be efficiently heated.

[0025] (Fourth aspect) a holding chamber for holding the molten metal; a holding chamber cover that closes an upper opening of the holding chamber; a slender molten metal heating body extending obliquely downward from a side wall portion of the holding chamber and heating the molten metal inside the holding chamber; a lower surface of a portion of the holding chamber cover located above the molten metal heating body is inclined in the same direction as the molten metal heating body while leaving a predetermined gap between the lower surface and the previous molten metal heating body; a lower limit liquid level of the molten metal in the holding chamber is set to a height equal to or higher than an upper end of the molten metal heater provided in the holding chamber, The molten metal is replenished into the holding chamber before the liquid level of the molten metal in the holding chamber falls below the lower limit liquid level, and the liquid level of the molten metal in the holding chamber is maintained at a height equal to or higher than the upper end of the molten metal heater. A molten metal holding furnace characterized by:

[0026] (Action and effect) The same effects as those of the first embodiment can be achieved.

[0027] (Fifth aspect) The molten metal holding furnace of the fourth aspect, wherein the inclination angle of the lower surface of the portion of the holding chamber cover located above the molten metal heater and the inclination angle of the molten metal heater are both within a range of 20 to 45 degrees.

[0028] (Action and effect) The same effects as those of the second embodiment can be achieved.

[0029] (Sixth aspect) The molten metal holding furnace of the first or fourth aspect, further comprising a liquid level sensor provided inside the holding chamber for detecting at least one of a drop in the liquid level of the molten metal inside the holding chamber to the lower limit liquid level and an approach to the lower limit liquid level.

[0030] (Action and effect) By providing the liquid level sensor inside the holding chamber, it is possible to quickly and accurately detect at least one of whether the liquid level of the molten metal inside the holding chamber has dropped to the lower limit liquid level or whether it is approaching the lower limit liquid level.

[0031] (Seventh aspect) A molten metal receiving chamber is provided to which the molten metal is supplied. The holding chamber is in communication with the receiving chamber and serves to hold the molten metal that has flowed in from the receiving chamber, The liquid level of the molten metal in the receiving chamber and the liquid level of the molten metal in the holding chamber are set to the same level, A liquid level sensor is provided inside the receiving chamber to detect at least one of the fact that the liquid level of the molten metal inside the holding chamber has fallen to the lower limit liquid level and the fact that the liquid level of the molten metal inside the holding chamber has approached the lower limit liquid level. The molten metal holding furnace according to the first or fourth aspect.

[0032] (Action and effect) Although the liquid level sensor may be provided inside the holding chamber as in the sixth embodiment, the upper opening of the holding chamber is generally covered with a thick lid, and the liquid level sensor must be installed by penetrating this lid, which is often not easy to install. For the same reason, when the liquid level sensor breaks down, it is often not easy to replace the liquid level sensor.

[0033] In the seventh embodiment, the level of the molten metal inside the receiving chamber and the level of the molten metal inside the holding chamber are at the same level, so that the level of the molten metal inside the holding chamber can be known by measuring the level of the molten metal inside the receiving chamber.

[0034] Therefore, in this embodiment, a liquid level sensor that detects when the liquid level of the molten metal inside the holding chamber has dropped to a lower limit liquid level is provided inside the receiving chamber. This configuration makes it easier to install and replace the liquid level sensor than when the liquid level sensor is provided inside the holding chamber. Furthermore, even in the embodiment where the liquid level sensor is provided inside the receiving chamber, it is possible to accurately detect when the liquid level of the molten metal inside the holding chamber has dropped to a lower limit liquid level.

[0035] In addition, a tapping chamber can be provided downstream of the holding chamber, the level of the molten metal inside the holding chamber and the level of the molten metal inside the tapping chamber can be set at the same level, and a level sensor can be provided inside the tapping chamber to detect when the level of the molten metal inside the holding chamber has dropped to a lower limit level.

[0036] However, it is more preferable to provide the level sensor in the receiving chamber rather than the tapping chamber as in this embodiment. If the molten metal in the tapping chamber is suddenly transferred to an external die-casting machine or the like by a ladle or the like, the level of the molten metal in the tapping chamber will drop suddenly temporarily. Even if the level of the molten metal in the tapping chamber drops significantly temporarily like this, the molten metal in the holding chamber will flow into the tapping chamber as time passes, and the level of the molten metal in the tapping chamber and the level of the molten metal in the holding chamber will eventually reach the same level and settle down. However, if a level sensor is provided in the tapping chamber, when the level of the molten metal in the tapping chamber drops significantly temporarily, the level sensor in the tapping chamber may erroneously recognize that the level of the molten metal in the holding chamber has also dropped significantly, and in some cases may erroneously recognize that the level of the molten metal in the holding chamber has fallen below the lower limit level.

[0037] The molten metal in the receiving chamber is less likely to have a sudden change in the level of the molten metal, as is the case with the molten metal in the tapping chamber. Therefore, since the level sensor in the receiving chamber is less likely to erroneously detect the above-mentioned problem, it is preferable to install the level sensor in the receiving chamber rather than the tapping chamber, as in this embodiment. Effect of the Invention

[0038] According to the present invention, it is possible to provide a molten metal holding furnace that can efficiently raise and maintain the temperature of molten metal held in the molten metal holding furnace, while suppressing adhesion of oxides to the molten metal heating element that heats the molten metal and suppressing the release of hydrogen gas bubbles into the molten metal. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 is a schematic plan view showing a molten metal storage furnace according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of the molten metal storage furnace taken along line Z1-Z1 in FIG. 1. [Diagram 3] 2 is a cross-sectional view of the molten metal storage furnace taken along line Z2-Z2 in FIG. 1. [Figure 4] 1. FIG. 4 is a cross-sectional view of a molten metal storage furnace according to a second embodiment, the cross-sectional view corresponding to line Z1-Z1 in FIG. [Diagram 5] FIG. 11 is a schematic plan view showing a molten metal storage furnace according to a third embodiment. [Figure 6] 6 is a cross-sectional view of the molten metal storage furnace taken along line Z3-Z3 in FIG. 5. [Figure 7] FIG. 13 is a schematic plan view showing a molten metal holding furnace according to a fourth embodiment. [Figure 8] 6 is a cross-sectional view of the molten metal storage furnace taken along line Z4-Z4 in FIG. 5. [Figure 9] FIG. 4 is a cross-sectional view showing a metal melting chamber according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, an embodiment of the present invention will be described.

[0041] A preferred embodiment of a molten metal storage furnace 1 according to the present invention will be described below with reference to the drawings. Note that the following description and the drawings merely show one example of an embodiment of the present invention, and the contents of the present invention should not be interpreted as being limited to this embodiment.

[0042] First embodiment A first embodiment of a molten metal storage furnace 1 according to the present invention is shown in Figures 1 to 3. This molten metal storage furnace 1 has a receiving chamber 11 for receiving molten metal MM such as an aluminum alloy, a holding chamber 13 for holding the molten metal, and a tapping chamber 16 for tapping the molten metal MM. A molten metal heater 2 is provided in the holding chamber 13. A holding chamber cover 13C for closing an upper opening of the holding chamber 13 is provided above the holding chamber 13.

[0043] (Holding room 13) The holding chamber 13 is the space inside a holding chamber container 13D, and the molten metal MM is held in this holding chamber 13. In order to prevent a decrease in the temperature of the molten metal MM in the holding chamber 13, a molten metal heater 2 is provided.

[0044] The molten metal heater 2 is not particularly limited, but it is preferable that it does not impede the movement of the molten metal MM, and an elongated heater is preferable rather than a plate-shaped heater. Specifically, it is preferable to use a tube-shaped heater such as a tube burner or a tube heater. There is no particular limit to the number of molten metal heaters 2 as long as the temperature of the molten metal MM can be appropriately maintained. In the first embodiment shown in FIG. 1, four molten metal heaters 2 are installed in the holding chamber 13.

[0045] The base end of the molten metal heating body 2 is provided on the side wall portion of the holding chamber 13. In the example of Fig. 3, the base end of the molten metal heating body 2 is attached to the upper part of the side wall 13Ds (side wall on the left side of the drawing) of the holding chamber container 13D and the upper part of the side wall (side wall on the left side of the drawing) of the insulating layer 13E located outside the holding chamber container 13D by penetrating the holding chamber container 13D and the insulating layer 13E. The molten metal heating body 2 extends from the side wall portion of the holding chamber 13 obliquely downward of the holding chamber 13. In the example of Fig. 3, the molten metal heating body 2 is provided so as to extend from the upper part of the side wall 13Ds (side wall on the left side of the drawing) of the holding chamber container 13D toward the opposite floor part 13Db (floor part on the right side of the drawing). That is, the molten metal heater 2 extends from an upper portion of a side wall 13Ds (the side wall on the left side in the drawing) of the holding chamber vessel 13D toward a lower portion of the opposite side wall 13Ds (the side wall on the right side in the drawing).

[0046] The inclination angle of the molten metal heater 2 can be determined arbitrarily, but the depression angle α between the axis 2x of the molten metal heater 2 and the imaginary horizontal line 2y is preferably set to 20 to 45 degrees, and more preferably 30 to 40 degrees.

[0047] When the angle α is less than 20 degrees, it is possible to reduce the height of the holding chamber 13. As a result, there is an advantage that it is possible to prevent the inconvenience of a decrease in the operating efficiency of existing equipment, etc., as described above.

[0048] However, if the height of the holding chamber 13 is made too low, it becomes necessary to change the heights of the receiving chamber 11 and the tapping chamber 16. In other words, if the heights of the receiving chamber 11 and the tapping chamber 16 are not changed, the heights of the chambers 11, 13, and 16 will differ greatly, causing the shapes of the flow paths (first flow path W1 and second flow path W2) of the receiving chamber 11 and the tapping chamber 16 connected to the holding chamber 13 to become distorted, making it difficult for the molten metal MM to flow between the chambers 11, 13, and 16.

[0049] In addition, there is no need to make the angle α of the molten metal heater 2 too small.

[0050] In addition, as the angle α of the molten metal heating body 2 becomes smaller, the extension direction of the molten metal heating body 2 becomes closer to horizontal, so it becomes necessary to increase the width of the holding chamber 13 in order to accommodate the molten metal heating body 2. As a result, there arises an inconvenience that a large space is required to install the holding chamber 13.

[0051] Furthermore, as the width of the holding chamber 13 increases, the area of ​​the bottom surface of the holding chamber 13 also tends to increase. If the area of ​​the bottom surface of the holding chamber 13 is large, there are disadvantages such as increased heat dissipation and a larger installation area.

[0052] From the above, it is preferable that the angle α of the molten metal heater 2 is set to 20 degrees or more.

[0053] On the other hand, if the angle α is greater than 45 degrees, the height of the holding chamber 13 that accommodates the molten metal heating body 2 cannot be reduced, which may result in the inconvenience of a decrease in the operating efficiency of existing equipment, etc., as described above.

[0054] In view of the above operational inconveniences, it is preferable to set the angle α to 45 degrees or less.

[0055] In the example of FIG. 3, the left and right side walls 13Ds of the holding chamber vessel 13D are almost vertical, and the floor 13Db on the right side of the drawing is almost horizontal. On the other hand, the floor 13Db on the left side of the drawing of the holding chamber vessel 13D is inclined downward from the left side to the right side of the drawing, similar to the molten metal heating body 2. It is preferable that the inclination angle β of the inclined floor surface 13Db1 of the floor 13Db of this holding chamber vessel 13D (the depression angle β between the extension line 13Dx of the inclined floor surface 13Db1 and the imaginary horizontal line 13Dy) is almost the same as the inclination angle α of the molten metal heating body 2. For example, when the inclination angle α of the molten metal heating body 2 is 35 degrees, the inclination angle β of the inclined floor surface 13Db1 is also preferably about 33 to 37 degrees, and most preferably 35 degrees. By adjusting the inclination angles α and β, the molten metal heating body 2 and the inclined bed surface 13Db1 can be made almost parallel, so that the distance X (the distance in the direction perpendicular to the axis 2x of the molten metal heating body 2) between the surface of the molten metal heating body 2 and the bed portion 13Db (inclined bed surface 13Db1) is almost the same at any point. As a result, heat can be uniformly transferred from the molten metal heating body 2 to the molten metal MM in the space Y between the molten metal heating body 2 and the inclined bed surface 13Db1, so that the molten metal MM can be heated uniformly.

[0056] That is, the molten metal MM tends to be more easily heated the closer it is to the molten metal heating body 2, which is the heat generation source, and in particular, the space Y between the surface of the molten metal heating body 2 and the inclined bed surface 13Db1 improves heating efficiency because the heat generated from the molten metal heating body 2 hits the inclined bed surface 13Db1 and is reflected back to the molten metal heating body 2. By making the distance X between the outer surface of the molten metal heating body 2 and the inclined bed surface 13Db1 approximately the same at any position in the axial direction of the molten metal heating body 2, the temperature in the space Y becomes approximately the same at any point, making it difficult for temperature unevenness to occur in the space Y.

[0057] In addition, the holding chamber 13 shown in FIG. 3 has a shorter distance X from the molten metal heater 2 to the floor 13Db below it, compared to the case in which the floor 13Db of the holding chamber 13 shown in FIG. 9 is not inclined. As a result, the embodiment shown in FIG. 3 can heat the molten metal MM in the space Y more easily than the embodiment shown in FIG. 9. Furthermore, since the holding chamber 13 shown in FIG. 3 can be made smaller than the holding chamber 13 shown in FIG. 9, as described above, moisture from the moldable refractory forming the holding chamber container 13D and the insulating layer 13E located outside the holding chamber container reacts with the molten metal MM and is taken into the molten metal MM in the form of hydrogen atoms, and the amount of hydrogen gas released into the molten metal MM as bubbles is also reduced, which inevitably suppresses the release of hydrogen gas bubbles.

[0058] 3, when an inclined floor surface 13Db1 is provided on the holding chamber vessel 13D, the distance X from the surface of the molten metal heater 2 to the inclined floor surface 13Db1 is preferably 7 to 13 cm, more preferably 10 to 11 cm. If the distance X is shorter than 7 cm, the space Y becomes too small, so that the amount of the molten metal MM in the space Y decreases, and as a result, there is a risk of the temperature unevenness becoming large in the holding chamber 13. On the other hand, if the distance X is longer than 13 cm, the space Y becomes too large, so that the amount of the molten metal MM in the space Y increases, resulting in undesirable phenomena such as a decrease in heating efficiency.

[0059] 9, the distance from the molten metal heating body 2 to the floor 13Db below it varies widely. In such cases, the distance X refers to the average distance from the molten metal heating body 2 to the floor 13Db below it.

[0060] 3, the floor portion 13Db of the holding chamber container 13D has a side extension surface 13Db2 that extends laterally from the lower end of the inclined floor surface 13Db1. This side extension surface 13Db2 extends laterally almost horizontally from the lower end of the inclined floor surface 13Db1.

[0061] If there is foreign matter (hereinafter, referred to as "unwanted matter") in the molten metal MM inside the holding chamber 13, this foreign matter will gradually accumulate on the floor 13Db of the holding chamber 13 due to gravity over time.

[0062] As shown in FIG. 3, by providing an inclined floor surface 13Db1 on the floor portion 13Db of the holding chamber 13, the unwanted objects that fall onto the inclined floor surface 13Db1 roll down along the inclination of the inclined floor surface 13Db1 and accumulate on the side extension surface 13Db2. That is, the unwanted objects do not scatter over the entire bottom surface of the holding chamber 13, but rather naturally gather on the side extension surface 13Db2. Therefore, when the opening cover 13Ca provided on the upper opening 13Ca1 of the holding chamber cover 13C is opened and a ladle or the like is inserted into the holding chamber 13 from the upper opening 13Ca1 to scoop up and collect the unwanted objects, the unwanted objects accumulated on the side extension surface 13Db2 can be scooped up, which can increase the efficiency of collecting the unwanted objects compared to the case where the inclined floor surface 13Db1 is not provided as in FIG. 9.

[0063] 1 and 3, it is preferable to provide a recessed portion (groove 13Db3) on side extending surface 13Db2. By providing such groove 13Db3, when collecting unwanted objects, the unwanted objects on side extending surface 13Db2 can be dropped into groove 13Db3, and then a ladle can be inserted into groove 13Db3 and moved along the extension direction of groove 13Db3, making it easy to collect the unwanted objects.

[0064] The upper opening 13Ca1 of the holding chamber cover 13C preferably has an inner peripheral surface that is inclined such that the opening area is gradually wider from the bottom to the top. The opening cover 13Ca preferably has an outer peripheral surface that is inclined corresponding to the inner peripheral surface of the upper opening 13Ca1 so that it can be fitted into the upper opening 13Ca1 from above. Compared to a case where the opening cover 13Ca and the upper opening 13Ca1 have vertical inner and outer peripheral surfaces, it is difficult to create a gap when fitting and oxidation is prevented, and the upper opening 13Ca1 can be easily closed by simply fitting the opening cover 13Ca into the upper opening 13Ca1 from above. In addition, when the opening cover 13Ca is lifted and removed for maintenance, the opening cover 13Ca can be prevented from falling to the bottom of the holding chamber 13. By fitting the opening cover 13Ca into the upper opening 13Ca1, the opening cover 13Ca functions as a part of the holding chamber cover 13C, so the opening cover 13Ca can also be said to be a part of the holding chamber cover 13C.

[0065] The space Y between the molten metal heater 2 and the inclined bed surface 13Db1 is also called an easily heated space, since it is a space in which the molten metal MM can be easily heated. Since the amount of the molten metal MM present in this easily heated space is not large, the heat of the molten metal heater 2 is transferred to the molten metal MM by contacting the surface of the molten metal heater 2, and the molten metal MM is easily heated.

[0066] The easily-heating space Y is at a higher temperature than the other spaces, and is a space that makes it easy to heat the molten metal MM if the temperature of the molten metal MM drops due to contact with the outside air when the molten metal MM is supplied to the molten metal storage furnace 1, or if the temperature of the molten metal MM in the receiving chamber 11 drops while it is stored in the receiving chamber 11. Also, this space allows the melting of metal pieces or metal lumps that have not been completely melted in the molten metal MM.

[0067] The molten metal MM maintained at the desired temperature in the holding chamber 13 in the above manner flows from the second flow path W2 into the discharge chamber 16, where it is prepared for discharge. The molten metal MM continues to flow into the discharge chamber 16 until the liquid levels of the molten metal MM in the receiving chamber 11, holding chamber 13, and discharge chamber 16 all reach the same level, at which point the flow naturally stops.

[0068] Thereafter, a portion of the molten metal MM in the tapping chamber 16 is tapped into a downstream device such as a casting machine or a die-casting machine.

[0069] In order to maintain the temperature of the molten metal MM, the holding chamber 13 preferably has a multi-layer structure in which the holding chamber container 13D, the insulating layer 13E, and the shell 13F are arranged in this order from the holding chamber 13 outward. The same applies to the receiving chamber 11 and the tapping chamber 16.

[0070] In order to prevent the temperature of the molten metal MM in the tapping chamber 16 from decreasing, it is preferable to provide a molten metal heating body 2 such as a heater inside the tapping chamber 16 as well.

[0071] It is preferable to set a lower limit liquid level L1 as a recommended lower limit value of the liquid level ML of the molten metal MM held in the holding chamber 13. It is preferable to set this lower limit liquid level L1 at a height equal to or higher than the upper end portion (hereinafter referred to as "upper end portion 2G") of the molten metal heating body 2. It is preferable to set this lower limit liquid level L1 at a position slightly higher than the upper end portion 2G of the molten metal heating body 2, rather than at the same height as the upper end portion 2G of the molten metal heating body 2.

[0072] This is because, if the liquid level sensor 17 detects that the molten metal MM in the holding chamber 13 has dropped to the lower limit liquid level L1 and then sends a message to refill the molten metal MM in the receiving chamber 11, if a large amount of molten metal MM is discharged from the discharge chamber 16 at once, the amount of molten metal MM in the holding chamber 13 may suddenly decrease and temporarily fall below the lower limit liquid level L1. In this case, if the lower limit liquid level L1 is set to the same height as the upper end 2G of the molten metal heating body 2, the upper end 2G of the molten metal heating body 2 will be temporarily exposed above the liquid level ML of the molten metal MM in the holding chamber 13 (until the molten metal MM is newly refilled), which may lead to a decrease in the heating efficiency of the molten metal heating body 2 and the adhesion of oxides. In order to prevent such a situation, it is preferable to set the lower limit liquid level L1 at a position slightly higher than the upper end 2G of the molten metal heating body 2.

[0073] If the lower limit liquid level L1 is set to the same level as the upper end 2G of the molten metal heating body 2, it is preferable to replenish new molten metal MM into the molten metal receiving chamber 11 as soon as possible when the liquid level sensor 17 detects that the molten metal MM in the holding chamber 13 is approaching the lower limit liquid level L1. In order to increase the reliability of preventing the upper end 2G of the molten metal heating body 2 from being temporarily exposed above the liquid level ML of the molten metal MM in the holding chamber 13, it is preferable to set the lower limit liquid level L1 at a position slightly higher than the upper end 2G of the molten metal heating body 2 and to replenish new molten metal MM into the molten metal receiving chamber 11 as soon as possible when the liquid level sensor 17 detects that the molten metal MM in the holding chamber 13 is approaching the lower limit liquid level L1.

[0074] As described above, it is preferable to provide the liquid level sensor 17 inside the holding chamber 13 and detect that the liquid level ML of the molten metal MM inside the holding chamber 13 is approaching the lower limit liquid level L1 or that the liquid level ML of the molten metal MM inside the holding chamber 13 has reached the lower limit liquid level L1 by the liquid level sensor 17. When such detection is performed, the information is transmitted to the control unit 20. It is preferable that the control unit 20, upon receiving the information, issues a command to the molten metal supply unit 21 to supply the molten metal MM, and the molten metal supply unit 21 supplies new molten metal MM in the commanded amount to the receiving chamber 11. Since the receiving chamber 11 and the holding chamber 13 are in communication with each other, when new molten metal MM is supplied into the receiving chamber 11, a part of the molten metal MM in the receiving chamber 11 flows into the holding chamber 13, and as a result, the liquid level ML in the holding chamber 13 can be raised again.

[0075] In this way, by constantly maintaining the liquid level ML of the molten metal MM inside the holding chamber 13 at or above the lower limit liquid level L1, it is possible to constantly maintain a state in which the entire molten metal heating body 2 inside the holding chamber 13 is immersed in the molten metal MM. As a result, it is possible to prevent the molten metal heating body 2 from heating anything other than the molten metal MM (such as the air AR) inside the holding chamber 13, and it is possible to increase the heating efficiency by the molten metal heating body 2.

[0076] Second Embodiment Next, a second embodiment will be described. A holding chamber 13 (second embodiment) different from the embodiment shown in Fig. 3 is shown in Fig. 4. The holding chamber 13 shown in Fig. 4 can be used in the molten metal storage furnace 1 of the first embodiment, similar to the holding chamber 13 in the embodiment shown in Fig. 3.

[0077] The holding chamber 13 in Fig. 4 is almost the same as the holding chamber 13 in Fig. 3, so a description of the same parts will be omitted and only the different parts will be described. The holding chamber 13 in Fig. 4 is characterized in that the lower surface 13Cb of the holding chamber lid 13C covering the holding chamber 13 is inclined. Specifically, the lower surface 13Cb of the holding chamber lid 13C located above the molten metal heating body 2 is inclined in the same direction as the molten metal heating body 2 while leaving a predetermined gap between them. This point will be described in detail below.

[0078] In the example of FIG. 4, a part of the lower surface 13Cb of the holding chamber cover 13C that covers the holding chamber 13 is inclined downward from the left side to the right side of the drawing, similar to the molten metal heater 2. Hereinafter, the lower surface 13Cb of the holding chamber cover 13C that is inclined in substantially the same direction as the molten metal heater 2 is referred to as the same-direction inclined lower surface 13Cb1, and the lower surface 13Cb of the holding chamber cover 13C that is inclined in a different direction from the molten metal heater 2 is referred to as the different-direction inclined or horizontal lower surface 13Cb2. It is preferable that the inclination angle θ of this same-direction inclined lower surface 13Cb1 (the depression angle θ between the extension line 13Cx of the same-direction inclined lower surface 13Cb1 and the virtual horizontal line 13Cy) is substantially the same as the inclination angle α of the molten metal heater 2. For example, when the inclination angle α of the molten metal heater 2 is 35 degrees, the inclination angle θ of the same-direction inclined lower surface 13Cb1 is also preferably about 33 to 37 degrees, and most preferably 35 degrees. By adjusting the inclination angles α and θ, the molten metal heater 2 and the same-direction inclined lower surface 13Cb1 of the holding chamber lid 13C can be made almost parallel, so that the distance P (the distance in the direction perpendicular to the axis 2x of the molten metal heater 2) between the surface of the molten metal heater 2 and the same-direction inclined lower surface 13Cb1 of the holding chamber lid 13C becomes almost the same at any point. As a result, heat can be uniformly transferred from the molten metal heater 2 to the molten metal MM flowing in the space Q between the molten metal heater 2 and the same-direction inclined lower surface 13Cb1 of the holding chamber lid 13C, so that the temperature unevenness of the molten metal MM can be reduced and efficient heating is possible. That is, the space Q between the surface of the molten metal heater 2 and the same-direction inclined lower surface 13Cb1 of the holding chamber lid 13C can exert the same effect as the space Y described above. The effect of reducing the temperature unevenness of the molten metal MM and enabling efficient heating by providing this space Q is the same as that of the easily heated space Y, so a detailed description will be omitted here.

[0079] In addition, when the holding chamber cover 13C is provided with a same-direction inclined lower surface 13Cb1 as shown in FIG. 4, the distance P from the surface of the molten metal heater 2 to the same-direction inclined lower surface 13Cb1 is preferably 7 to 13 cm, more preferably 10 to 11 cm. If the distance P is shorter than 7 cm, the space Q becomes too small, so that the amount of the molten metal MM flowing in the space Q per unit time decreases, and as a result, the temperature unevenness in the holding chamber 13 increases, and the heating efficiency may decrease. On the other hand, if the distance P is longer than 13 cm, the speed of the molten metal MM flowing in the space Q does not increase, so that the amount of the molten metal MM contacting the surface of the molten metal heater 2 on the space Q side decreases, and therefore the heat from the molten metal heater 2 is not easily transferred to the molten metal MM, which may decrease the heating efficiency of the molten metal MM and increase the temperature unevenness.

[0080] Third embodiment Next, a third embodiment will be described. Figures 5 and 6 show a molten metal storage furnace 1 according to a third embodiment. This third embodiment is significantly different from the first embodiment in that a liquid level sensor 17 is provided in the molten metal receiving chamber 11, rather than in the holding chamber 13.

[0081] The upper opening of the holding chamber 13 is often covered by a thick holding chamber lid 13C, and it is often not easy to penetrate the holding chamber lid 13C to install the liquid level sensor 17. In addition, since the holding chamber lid 13C is not basically designed to be opened and closed, even if the liquid level sensor 17 breaks down, it is often not easy to replace the liquid level sensor 17.

[0082] On the other hand, since the molten metal MM is often supplied to the receiving chamber 11, the upper opening of the receiving chamber 11 is often not provided with a lid, or if provided, a lid that is easy to open and close is often provided. Therefore, it is relatively easy to provide a liquid level sensor 17 in the receiving chamber 11. Therefore, in the third embodiment, the liquid level sensor 17 is provided in the receiving chamber 11.

[0083] Since the receiving chamber 11 and the holding chamber 13 are connected to each other, the liquid level of the molten metal MM inside the receiving chamber 11 and the liquid level of the molten metal MM inside the holding chamber 13 are basically at the same level.

[0084] As shown in FIG. 6, a lower limit level L1 of the same height as the lower limit level L1 set in the holding chamber 13 is also set in the receiving chamber 11, and the lower limit level L1 of the receiving chamber 11 can be detected using the level sensor 17 of the receiving chamber 11. When the level sensor 17 of the receiving chamber 11 detects that the level ML of the molten metal MM in the receiving chamber 11 has dropped to the lower limit level L1, it is preferable to estimate that the level ML of the molten metal MM in the holding chamber 13 has also dropped to the lower limit level L1 (this estimation is generally highly accurate), and to additionally replenish new molten metal MM into the receiving chamber 11 by the control unit 20. With this configuration, the level ML of the molten metal MM in the holding chamber 13 can be always maintained at or above the lower limit level L1.

[0085] In the above explanation, new molten metal MM is replenished into the receiving chamber 11 after the level sensor 17 detects that the level ML of the molten metal MM in the receiving chamber 11 has dropped to the lower limit level L1. However, if a large amount of molten metal MM is tapped from the tapping chamber 16 at once, the level ML of the molten metal MM in the receiving chamber 11 may suddenly drop. Therefore, it is preferable to replenish new molten metal MM into the receiving chamber 11 as soon as possible when the level ML of the molten metal MM in the receiving chamber 11 is approaching the lower limit level L1. By doing so, it becomes easier to always keep the level ML of the molten metal MM in the holding chamber 13 above the lower limit level L1.

[0086] It is also preferable to provide the liquid level sensor 17 in the receiving chamber 11 rather than in the outlet chamber 16. The reasons for this are as described above, and will not be explained here. In addition, other configurations of the third embodiment are similar to those of the first and second embodiments, and therefore explanations of the other configurations will also be omitted.

[0087] Fourth embodiment A molten metal storage furnace 1 according to the fourth embodiment is shown in Figs.

[0088] In this molten metal storage furnace 1, first, the molten metal MM is charged into the receiving chamber 11, and the molten metal MM in the receiving chamber 11 flows through the first flow path W1 into the holding chamber 13. In the holding chamber 13, the molten metal MM is heated by a molten metal heater 2 (e.g., a heater), and the temperature of the molten metal MM is maintained or increased. Then, the molten metal MM that has been maintained or increased in temperature in the holding chamber 13 flows through the second flow path W2 into the tapping chamber 16.

[0089] The flow of the molten metal MM from the holding chamber 13 to the tapping chamber 16 is controlled by a lift-up type shutoff valve 4 (a shutoff valve other than a lift-up type may be used; the same applies below) for opening and closing the second flow path W2. The lift-up type shutoff valve 4 can be provided at any location, such as the outlet of the holding chamber 13 for the molten metal MM, the inlet of the tapping chamber 16 for the molten metal MM, or the second flow path W2 as shown in FIG.

[0090] When the liquid level ML of the molten metal MM in the tapping chamber 16 is low, the lift-up type shutoff valve 4 is kept open, and when a sufficient amount of the molten metal MM has accumulated in the tapping chamber 16, the lift-up type shutoff valve 4 is closed.

[0091] Thereafter, when the molten metal MM in the tapping chamber 16 is to be sent to an external device (such as a die-casting machine, not shown) provided downstream, pressurized gas is supplied to the pressurizing section 33 in the tapping chamber 16 via the pressurized gas flow path 36. The pressurized gas thus supplied causes the liquid level ML in the pressurizing section 33 to drop, and the liquid level ML in the tapping section 34 in the tapping chamber 16 to rise, and the molten metal MM is supplied from the tapping section 34 to the external device. At this time, since the lift-up shutoff valve 4 is closed, it is possible to prevent the molten metal MM in the tapping chamber 16 from flowing back into the holding chamber 13 when pressurized by the pressurized gas. After a certain amount of the molten metal MM has been supplied to the external device in this manner, the supply of the pressurized gas is stopped. Then, the pressurized gas in the pressurizing section 33 is discharged to the outside via the pressurized gas flow path 36. As the pressurized gas is exhausted from the pressurizing part 33 in this manner, the liquid level ML in the tapping part 34 gradually drops, and the liquid level ML in the pressurizing part 33 gradually rises.

[0092] As described above, the liquid level ML often fluctuates in the pressurizing section 33 and the tap section 34. This fluctuation in the liquid level ML may damage the tap chamber container 16D of the tap chamber 16. That is, the tap chamber container 16D is often porous and breathable, and when pressurized gas is supplied into the tap chamber 16, a large pressure is applied especially in the range of the fluctuation of the liquid level ML, and cracks and damage are likely to occur in the above-mentioned fluctuation range of the tap chamber container 16D. Therefore, it is preferable to install a protective plate 37 made of fine ceramics or the like on the inner surface of the tap chamber container 16D in the height range where the liquid level ML of the pressurizing section 33 and the tap section 34 of the tap chamber 16 may fluctuate, to prevent the above-mentioned cracks and damage from occurring.

[0093] It is also important to operate the pressurizing unit 33 so that the liquid level ML fluctuates within the range in which the protective plate 37 is installed. For this reason, it is preferable to provide a level sensor 35 in the pressurizing unit 33 for detecting the liquid level ML of the molten metal MM in the pressurizing unit 33, and to measure the liquid level ML in the pressurizing unit 33 with the level sensor 35 when the lift-up shutoff valve 4 is opened to supply the molten metal MM into the tapping chamber 16 or when pressurized gas is supplied to the pressurizing unit 33 in the tapping chamber 16, and to control the liquid level ML to move within the range in which the protective plate 37 is installed.

[0094] In addition, the base end 14F of the molten metal heating body 2 (more specifically, the lower end of the base end 14F of the molten metal heating body (referred to as the "lower base end 14Ft of the molten metal heating body") should preferably be at least higher than the liquid level ML. This is because, even if the molten metal heating body 2 is damaged in this state and the molten metal MM invades the molten metal heating body 2, the invaded molten metal MM will not exceed the lower base end 14Ft of the molten metal heating body.

[0095] 1, 2, 5, 6, 7 and 8, in order to prevent the temperature of the molten metal MM in the tapping chamber 16 from decreasing, it is preferable to provide a molten metal heating body 2 such as a heater inside the tapping chamber 16. In this case, the shape of the molten metal heating body 2 and the bottom surface of the tapping chamber 16 may be the same as the molten metal heating body 2 and the holding chamber container 13D in the holding chamber 13. That is, when the heating efficiency of the molten metal heating body 2 in the tapping chamber 16 is important, it is preferable to dispose the molten metal heating body 2 so as to extend obliquely downward from the side wall of the tapping chamber 16 in the same manner as in the shape shown in FIG. 3, and to make the bottom surface of the tapping chamber 16 located below the molten metal heating body 2 into an inclined floor surface inclined in the same direction as the molten metal heating body 2 so as to be approximately parallel to the molten metal heating body 2. In this case, an easily-heatable space is formed between the inclined floor surface of the tapping chamber 16 and the molten metal heating body 2, and the heat of the molten metal heating body 2 is transferred to the molten metal MM by the molten metal MM in the easily-heatable space coming into contact with the surface of the molten metal heating body 2.

[0096] (Comparative Example) A holding chamber 13 according to a comparative example is shown in Fig. 9. The comparative example in Fig. 9 is shown to compare with the above-described embodiments and to explain the effects of these embodiments, and does not represent a conventionally known holding chamber 13. [Industrial Applicability]

[0097] The molten metal may be aluminum or an aluminum alloy, or may be another molten metal MM.

[0098] The technical scope of the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the molten metal holding furnace 1 of the present invention can be used in metal molten metal furnaces, melting furnaces, holding furnaces, low-pressure casting furnaces, etc. [Explanation of symbols]

[0099] 1...molten metal holding furnace, 2...molten metal heater, 2G...upper end of molten metal heater (inside holding chamber), 2x...axis of molten metal heater, 2y...imaginary horizontal line (of molten metal heater), 3...supply port of molten metal, 4...lifting shutoff valve, 5...discharge port of molten metal, 11...receiving chamber, 11D...receiving chamber container, 13...holding chamber, 13C...holding chamber lid, 13Ca...opening lid, 13Ca1...upper opening (of holding chamber lid), 13Cb...lower surface of holding chamber lid, 13Cb1...same direction Synchronically inclined lower surface, 13Cb2...Different direction inclined or horizontal lower surface, 13Cx...Extension line of the same direction inclined lower surface, 13Cy...Virtual horizontal line (of the same direction inclined lower surface), 13D...Holding chamber container, 13Db...(Holding chamber) floor, 13Db 1...Slanted floor surface, 13Db2...Side extension surface, 13Db3...Groove, 13Dx...Extension line of the sloped floor surface, 13Ds...Side wall (of the holding chamber), 13Dy...Virtual horizontal line (of the sloped floor surface), 13E...Thermal insulation layer, 13F...Iron skin, 14F ...base end of molten metal heater, 14Ft...bottom end of base end of molten metal heater, 16...discharging chamber, 16D...discharging chamber container, 17...lower limit liquid level, 20...control unit, 21...molten metal supply unit, 33...pressurizing unit, 34...discharging unit, 35...level sensor, 36...pressurized gas flow path, 37...protective plate, AR...air between the bottom surface of the lid and the surface of the molten metal, ML...liquid level, MM...molten metal, P...distance between the upper surface of the molten metal heater and the bottom surface of the lid inclined in the same direction distance, Q...easy to heat space (upper easily heated space), W1...first flow path, W2...second flow path, X...distance between the lower surface of the molten metal heating body and the inclined floor, Y...easy to heat space (lower easily heated space), α...inclination angle of the molten metal heating body, β...inclination angle of the inclined floor, θ...inclination angle of the inclined lower surface in the same direction, DD...depth direction, FS...front side, BS...rear side, HD...height direction, DS...lower side (lower), US...upper side (upper), WD...width direction, LS...left side, RS...right side

Claims

1. a holding chamber for holding the molten metal; a slender molten metal heating body extending obliquely downward from a side wall portion of the holding chamber and heating the molten metal inside the holding chamber; a bottom surface of the holding chamber located below the molten metal heating body has an inclined floor surface that is inclined in the same direction as the molten metal heating body while being spaced a predetermined distance from the molten metal heating body, A space that is easily heated is formed between the molten metal heater and the inclined bed surface, The molten metal in the easily-heatable space is in contact with a surface of the molten metal heater, so that heat from the molten metal heater can be transferred to the molten metal, a lower limit liquid level of the molten metal in the holding chamber is set to a height equal to or higher than an upper end of the molten metal heater provided in the holding chamber, The molten metal is replenished into the holding chamber before the liquid level of the molten metal in the holding chamber falls below the lower limit liquid level, and the liquid level of the molten metal in the holding chamber is maintained at a height equal to or higher than the upper end of the molten metal heater. A molten metal holding furnace characterized by:

2. 2. The molten metal holding furnace according to claim 1, wherein the inclination angle of said molten metal heater and the inclination angle of said inclined bed surface are both within a range of 20 to 45 degrees.

3. 2. The molten metal holding furnace according to claim 1, further comprising a holding chamber lid for closing an upper opening of the holding chamber, the lower surface of the portion of the holding chamber lid located above the molten metal heating body being inclined in the same direction as the molten metal heating body while leaving a predetermined distance between the molten metal heating body and the holding chamber lid.

4. a holding chamber for holding the molten metal; a holding chamber cover that closes an upper opening of the holding chamber; a slender molten metal heating body extending obliquely downward from a side wall portion of the holding chamber and heating the molten metal inside the holding chamber; a lower surface of a portion of the holding chamber cover located above the molten metal heating body is inclined in the same direction as the molten metal heating body while leaving a predetermined gap between the lower surface and the previous molten metal heating body; a lower limit liquid level of the molten metal in the holding chamber is set to a height equal to or higher than an upper end of the molten metal heater provided in the holding chamber, The molten metal is replenished into the holding chamber before the liquid level of the molten metal in the holding chamber falls below the lower limit liquid level, and the liquid level of the molten metal in the holding chamber is maintained at a height equal to or higher than the upper end of the molten metal heater. A molten metal holding furnace characterized by:

5. 5. The molten metal holding furnace according to claim 4, wherein the inclination angle of the lower surface of the portion of said holding chamber cover located above said molten metal heater and the inclination angle of said molten metal heater are both within the range of 20 to 45 degrees.

6. 5. The molten metal holding furnace according to claim 1, further comprising a liquid level sensor disposed inside the holding chamber for detecting at least one of a state in which the liquid level of the molten metal inside the holding chamber has dropped to the lower limit liquid level and a state in which the liquid level of the molten metal inside the holding chamber has approached the lower limit liquid level.

7. A molten metal receiving chamber is provided to which the molten metal is supplied. The holding chamber is in communication with the receiving chamber and serves to hold the molten metal that has flowed in from the receiving chamber, The liquid level of the molten metal in the receiving chamber and the liquid level of the molten metal in the holding chamber are set to the same level, A liquid level sensor is provided inside the receiving chamber to detect at least one of the fact that the liquid level of the molten metal inside the holding chamber has fallen to the lower limit liquid level and the fact that the liquid level of the molten metal inside the holding chamber has approached the lower limit liquid level.

5. The molten metal holding furnace according to claim 1 or 4.

Images