Metal melt filtering device

Abstract

The utility model provides a metal melt filtering device which can further homogenize / improve the metal melt stirring performance, the gas inclusion degassing performance and the pore channel blocking prevention performance of a filtering pipe. The disclosed molten metal filtration device comprises: (i) a filtration chamber which is provided with a molten metal inlet and a molten metal outlet, and which includes a hearth and an inner wall surface; (ii) a filter unit comprising a plurality of ceramic filter tubes for filtering out impurities from the molten metal, the ceramic filter tubes being disposed above the hearth inside the filter chamber; and (iii) a rotor disposed adjacent to the filter units, the rotor being disposed adjacent to each of the plurality of filter units in the presence of the plurality of filter units, the rotor stirring the molten metal by rotating in a substantially horizontal direction; the hearth is located at the lowest position substantially directly below the rotor when viewed in the horizontal direction, except for the location where the discharge flow path is provided, and as a result, substantially the entire contact portion of the hearth and the inner wall surface is located at a position higher than the lowest position substantially directly below the rotor.

Description

Technical Field

[0001] The utility model relates to a molten metal filtering device for filtering molten metals such as aluminum. Background Art

[0002] In molten metals such as aluminum used for manufacturing castings, non-metallic inclusions such as hydrogen and oxides are usually contained as impurities. For example, dissolved hydrogen in the molten metal forms casting holes called gas holes in the casting, and oxides and the like may become inclusions in the casting. These casting holes and inclusions may all become the starting points of casting failure, so they are not desirable. Therefore, filtering devices for filtering molten metals to remove inclusions and the like contained in the molten metals have been developed. In the molten metal filtering device, the molten metal in a state of being heated and melted at a high temperature is filtered. At this time, the filtering efficiency is usually affected by the melt temperature of the molten metal. Therefore, conventionally, the improvement of the filtering efficiency and further the improvement of the anti-clogging performance of the filter have been pursued by making the melt temperature more uniform in the filtering chamber of the molten metal filtering device.

[0003] For example, Patent Document 1 and Patent Document 2 disclose molten metal filtering devices for achieving such purposes.

[0004] That is, Patent Document 1 discloses a molten metal filtering device that filters using a ceramic filter tube group of a filtering unit disposed in a filtering chamber. A seat block capable of making the lowermost ceramic filter tube substantially the same height as the upper edge of the inlet or slightly higher than the upper edge of the inlet is disposed on the bottom wall at the lower position of the filtering unit. The filtering unit is disposed on the seat block, and in the vicinity of the filtering unit, injection nozzles are disposed so that the molten metal can be made to flow by gas injection. In addition, Patent Document 2 discloses a molten metal filtering device having the same structure as that of Patent Document 1, and fixing the injection nozzle to the lower end of a hollow shaft suspended from a lid body, and configuring it to be movable up and down together with the hollow shaft.

[0005] In Patent Document 1 and Patent Document 2, it is taught that by providing these structures in the molten metal filtering device, the effects of improving the filtering efficiency and the anti-clogging performance of the filter brought about by the uniformization of the melt temperature can be obtained. In this device, gas inclusions such as hydrogen are degassed using the ejected gas from the injection nozzle, and the outer surface of the ceramic filter tube is further cleaned, thereby preventing pore blockage.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 7-004868

[0009] Patent Document 2: Japanese Patent Laid-Open No. 7-003348 Summary of the utility model

[0010] Problems to be solved by the utility model

[0011] Figure 1 Fig. shows a schematic longitudinal sectional view of a part of the molten metal filtering device of Patent Document 1 (except for the structure related to the injection nozzle, the general situation of the molten metal filtering device of Patent Document 2 is also the same as this). This figure is equivalent to a figure obtained by simplifying / abstracting a part of Figure 2 of Patent Document 1. In this figure, F is the filtration chamber, T is the ceramic filter tube (a plurality of aggregates), I is the inlet of the molten metal, U is the filtration unit, N is the injection nozzle, W is the inner wall surface of the filtration chamber, B is the bottom surface of the filtration chamber (referred to as the hearth), and L is the imaginary line of the molten metal level (liquid level) when the molten metal is supplied to the filtration chamber.

[0012] According to this figure, when observing in the horizontal direction in a state where the molten metal filtering device is arranged on a horizontal plane, the bottom surface B of the filtration chamber F, which is referred to as the hearth, continuously decreases from the side of the inlet I toward the inner wall surface W on the opposite side of the filtration chamber, and the injection nozzle (which may include a rotor driven by a motor) N is arranged above the approximate middle position of this inclination. This continuous inclination of the hearth of the filtration chamber is provided to allow the molten metal to flow down naturally from the filtration chamber F by gravity and be discharged.

[0013] However, the inclination of the hearth B of the filtration chamber F causes the molten metal level (the depth from the molten metal surface to the hearth) on the hearth B to be different from the side of the inlet I toward the inner wall surface W on the opposite side of the filtration chamber F. Thus, the molten metal level at each position on the hearth of the filtration chamber is different, and as a result, non-uniform convection is locally generated. At the position with a higher molten metal level on the opposite side of the inlet I, the bubble density of the ejected gas from the injection nozzle becomes smaller, and there will be a deterioration and insufficiency of the degassing performance of gas inclusions such as hydrogen and the performance of preventing pore blockage achieved by cleaning the outer surface of the ceramic filter tube.

[0014] Moreover, since the performance of preventing pore blockage of the ceramic filter tube achieved by the ejected gas is different at each different position on the hearth of the filtration chamber, the service life of the filtration performance of the ceramic filter tube also varies in length, and the overall operating efficiency of the filtering device decreases.

[0015] Therefore, the problem to be solved by the present utility model is to provide such a molten metal filtering device that eliminates the above-mentioned drawbacks, that is, at different positions on the furnace bed of the filtering chamber, the stirring performance of the molten metal, the degassing performance of gas inclusions such as hydrogen, and the anti-channel clogging performance of the ceramic filter tubes are more uniform and further improved. As a result, the service life of the filtering performance of the ceramic filter tubes is also homogenized.

[0016] Means for Solving the Problem

[0017] The inventor has conducted in-depth research and found that by making the molten metal filtering device include a filtering chamber and one or more filtering units, and further including a rotor, the filtering chamber has an inlet and an outlet for the molten metal, and includes a furnace bed and an inner wall surface. The filtering unit is composed of a plurality of ceramic filter tubes arranged above the furnace bed in the filtering chamber for filtering out impurities from the molten metal. The rotor is arranged adjacent to the filtering unit (where there are multiple filtering units, it is adjacent to each filtering unit). The rotor stirs the molten metal by rotating in a substantially horizontal direction. And when observing the molten metal filtering device in a state where it is arranged on a horizontal plane from the horizontal direction, the furnace bed is designed such that the position directly below the rotor is the lowest height except for the position where the discharge flow path is provided, the above-mentioned problem can be solved. That is, the inventor has found that with a molten metal filtering device having such a structure, at different positions on the furnace bed of the filtering chamber (either in the part near the inlet or on the opposite side), a stable and uniformly distributed convection of the molten metal without local stagnation will occur. The degassing performance of gas inclusions such as hydrogen and the anti-channel clogging performance achieved by cleaning the outer surface of the ceramic filter tubes are improved. Moreover, at different positions on the furnace bed of the filtering chamber, the anti-channel clogging performance of the ceramic filter tubes is homogenized. As a result, the difference in the service life of the filtering performance of the ceramic filter tubes becomes smaller, and the overall operating efficiency of the filtering device is improved, thus completing the present utility model.

[0018] A typical embodiment of such a present utility model is as follows.

[0019] A molten metal filtering device, comprising:

[0020] (i) A filtering chamber having an inlet and an outlet for the molten metal and including a furnace bed and an inner wall surface;

[0021] (ii) A filtering unit composed of a plurality of ceramic filter tubes arranged above the furnace bed in the filtering chamber for filtering out impurities from the molten metal; and

[0022] (iii) A rotor disposed adjacent to the filtration unit(s), wherein in the case of multiple filtration units, the rotor is disposed adjacent to each of the multiple filtration units, and the rotor stirs the molten metal by rotating in a substantially horizontal direction;

[0023] Except for the location where the discharge flow path is provided, the hearth is at the lowest position directly below the rotor when viewed horizontally, whereby substantially the entire contact portion between the hearth and the inner wall surface is at a position higher than the lowest position directly below the rotor.

[0024] Utility Model Effects

[0025] The molten metal filtration device according to the present utility model includes a rotor disposed adjacent to the filtration unit(s), wherein in the case of multiple filtration units, the rotor is disposed adjacent to each of the multiple filtration units, and the rotor stirs the molten metal by rotating in a substantially horizontal direction. And when viewed horizontally in a state where the molten metal filtration device is disposed on a horizontal plane, the hearth is designed such that except for the location where the discharge flow path is provided, the position directly below the rotor is at the lowest height. Thus, at different positions on the hearth of the filtration chamber (either at the part near the liquid inlet or the opposite side thereof), a stable and uniform convection of the molten metal without local stagnation is generated. Furthermore, the degassing performance of gas inclusions such as hydrogen and the performance of preventing pore blockage achieved by cleaning the outer surface of the ceramic filtration tube are further improved. And at different positions on the hearth of the filtration chamber, the performance of preventing pore blockage of the ceramic filtration tube is homogenized. Consequently, the difference in the service life of the filtration performance of the ceramic filtration tube becomes smaller, the operating efficiency of the entire filtration device is improved, and excellent advantages that cannot be foreseen from the structure of the existing molten metal filtration device can be obtained. Description of the Drawings

[0026] Figure 1 A schematic / conceptual diagram of a partial longitudinal cross-sectional side view of the molten metal filtration device disclosed in Patent Document 1, Japanese Unexamined Patent Application Publication No. 7-004868 (prior art).

[0027] Figure 2 A schematic / conceptual diagram of a longitudinal cross-sectional side view of the molten metal filtration device according to an embodiment of the present utility model.

[0028] Figure 3 A longitudinal cross-sectional side view of the molten metal filtration device according to an embodiment of the present utility model.

[0029] Figure 4 Shows Figure 3 A - A cross-sectional view of the molten metal filtration device.

[0030] Figure 5 Shows Figure 3 A B-B cross-sectional view of the metal melt filtration device of

[0031] Figure 6 Figures (a) to (f) of are diagrams illustrating various embodiments of the rising portion formed on the bottom surface (hearth) of the filtration chamber of the metal melt filtration device of the present utility model. Detailed implementation manners

[0032] Use Figure 2 The schematic longitudinal cross-sectional side view (conceptual diagram) shown in is used to explain the metal melt filtration device of an embodiment of the present utility model. Figure 2 It is a view obtained by observing the longitudinal cross-sectional side of the device in the horizontal direction in a state where the metal melt filtration device is arranged in the horizontal plane.

[0033] In Figure 2 : 1 is the metal melt filtration device, 2 is the filtration chamber, 3 is the liquid inlet, 4 is the liquid outlet, 5 is the bottom surface of the filtration chamber (hereinafter referred to as the hearth), 6 is the inner wall surface of the filtration chamber, 7 is the heater, 8 is the filtration unit composed of a plurality of ceramic filtration tubes 8a above the hearth 5, 9 is the rotor arranged adjacent to the filtration unit 8, and H is a horizontal line representing the horizontal direction. The plurality of ceramic filtration tubes 8a are horizontally arranged in the paper surface direction at a specified interval. In this figure, as a typical example, 2 filtration units are provided, but the number of filtration units can also be 1, or more than 3. Matters described below for the embodiment with 2 filtration units can be equally applied to the embodiments with 1 or more than 3 filtration units as long as there are no technically unacceptable reasons.

[0034] When the metal melt is fed and filtered, as shown by the arrows in Figure 2 : The metal melt such as aluminum or aluminum alloy containing non-metallic inclusions is supplied from the liquid inlet 3 into the filtration chamber 2. The metal melt is heated by the heater 7 and at the same time, the non-metallic inclusions are filtered out by the ceramic filtration tubes 8a of the filtration unit 8. Then, the purified liquid of the metal melt after the filtration treatment is discharged from the liquid outlet 4. During the filtration treatment in the filtration chamber, the metal melt is stirred by the rotation of the rotor 9 in the substantially horizontal direction to achieve the uniformization of the melt temperature.

[0035] With the molten metal filtration device 1 having such a structure, the following advantages can be obtained: when the molten metal is fed and filtered, on either the part of the hearth 5 in the filtration chamber 2 near the liquid inlet 3 or its opposite side, the molten liquid level on the hearth is relatively lower compared to directly below the rotor 9 (the depth from the molten liquid surface to the hearth becomes smaller). Even at a position far from the rotor 9, a stable and uniform convection of the molten metal without local stagnation is generated. As a result, the degassing performance of gas inclusions such as hydrogen and the performance of preventing pore blockage achieved by cleaning the outer surface of the ceramic filter tube 8a are further improved.

[0036] In addition, when the molten metal is fed and filtered, on either the part of the hearth 5 in the filtration chamber 2 near the liquid inlet 3 or its opposite side, the molten liquid level is relatively lower compared to directly below the rotor 9. At different positions on the hearth 5 of the filtration chamber 2, the performance of preventing pore blockage of the ceramic filter tube becomes more uniform. As a result, the difference in the service life of the filtration performance of the ceramic filter tube 8a becomes smaller.

[0037] Use Figures 3 to 5 A further description is given of the molten metal filtration device according to an embodiment of the present utility model. Figure 3 It is a view of the longitudinal sectional side of the device observed horizontally in a state where the molten metal filtration device is arranged on a horizontal plane. Figure 4 Shows Figure 3 The A - A cross-sectional view of the molten metal filtration device of Figure 5 Shows Figure 3 The B - B cross-sectional view of the molten metal filtration device of

[0038] In addition, in Figures 3 to 5 for the component groups that are functionally interconnected, the same reference signs are used. Figure 2 In

[0039] In Figures 3 to 5 1 is the molten metal filtration device, 2 is the filtration chamber, 3 is the liquid inlet, 4 is the liquid outlet, 5 is the bottom surface (hearth) of the filtration chamber composed of a flat portion 5a near the center of the hearth (directly below the rotor), a rising portion 5b, and a discharge flow path 5c, 6 is the inner wall surface of the filtration chamber, 7 is the heater, 8 is a filtration unit composed of a plurality of ceramic filter tubes 8a above the hearth 5 and having a wedge member 8b, 9 is a rotor composed of a motor 9a, a rotating rod 9b, and a front end member 9c, 10 is the pedestal of the filtration unit 8, 11 is the housing of the filtration chamber that houses the filtration chamber 2, and M is an imaginary line of the molten liquid surface of the molten metal when the molten metal is injected into the filtration chamber 2 for filtration.

[0040] In Figures 3 to 5Among them, as a typical example, two filtering units are provided. However, the number of filtering units can also be one, or can be three or more. A plurality of ceramic filter tubes 8a are horizontally arranged in the paper surface direction at a prescribed interval. Except for the liquid inlet 3, the liquid outlet 4, and the vicinity of the motor 9a of the rotor 9, substantially the whole of the filtering chamber 2 is accommodated by the housing 11 of the filtering chamber. The housing 11 of the filtering chamber is generally formed of metal substantially as a whole, and is also called a tank body.

[0041] Generally, as Figure 3 shown by the arrow in [figure], a metal melt such as aluminum or an aluminum alloy containing non-metallic inclusions, which is heated to about 500 °C or more to about 800 °C, is supplied from the liquid inlet 3 into the filtering chamber 2. The opening area of the liquid inlet 3 is appropriately designed according to the desired filtering throughput of the metal melt filtering device 1. The liquid inlet 3 is preferably connected to a flow-down path, which is formed obliquely or substantially vertically so that the supplied metal melt can flow down by gravity.

[0042] The metal melt entering from the liquid inlet 3 is preferably kept warm or further heated to a high temperature by a heater 7 provided in the filtering chamber. As the heater 7, in the figure, several long cylindrical heaters are vertically provided at substantially equal intervals near the inner wall surface 6 having the liquid inlet 3 in the filtering chamber 2 and near the inner wall surface 6 on the side opposite to the liquid inlet 3, respectively. Regarding the heater 7, as long as it can heat the metal melt, it is not limited to the illustrated shape, number, or installation position. For example, its cross-sectional shape can be partially or wholly elliptical or rectangular. In addition, regarding the heater 7, at a prescribed position, a single heater can be provided, or multiple heaters (for example, 2 to 20 heaters) can be provided. Further, the heater can be provided at a position away from the inner wall surface. When the heater 7 is provided near the inner wall surface 6 having the liquid inlet 3 in the filtering chamber 2, in order to prevent unevenness in the life of multiple tubes and a reduction in filtering efficiency caused by direct contact between the metal melt and the ceramic filter tubes 8a of the adjacent filtering unit 8, it is preferable to provide a shielding wall (not shown) between the heater 7 at this position and the filtering unit 8.

[0043] The filtering chamber 2 is not particularly limited. Typically, on its inner surface, a hexahedron such as a substantially rectangular parallelepiped or a substantially cube can be formed. The inner surface of the filtering chamber 2 is formed by a hearths 5 as its bottom surface, the inner wall surfaces 6 of the surrounding filtering chamber, and a cover body covering above them (the bottom surface of the cover body constitutes the top surface of the filtering chamber). The inner wall surface 6 preferably forms a wall surface in a substantially vertical direction (vertical direction with respect to the horizontal plane).

[0044] As Figures 3 to 5As shown, pedestals 10 are disposed at specified positions (usually multiple positions) near the inner wall surface 6 on the hearth 5 of the filtration chamber 2. A filtration unit 8 (although two are shown in the figure, it can also be a single one or three or more) is stably placed / fixed on the pedestal 10. Regarding the shape and number of the pedestals 10 for the filtration unit 8 (single or multiple), as long as the filtration unit 8 can be fixed firmly (in a non-moving manner) substantially horizontally, there is no particular limitation. When multiple pedestals 10 are disposed, preferably, they are arranged at positions corresponding to each other with respect to the respective surfaces of the inner wall surface 6 in their vicinity. Additionally, as Figure 4 and Figure 5 shown, the filtration unit 8 can also be fixed to the inner wall surface 6 via a wedge member 8b. The shape of the wedge member 8b is configured to be able to fix the filtration unit 8 to the inner wall surface 6 with high durability, and the number thereof can be one or two or more (in Figure 5 an example of setting three wedge members 8b for one filtration unit 8 is illustrated).

[0045] Each filtration unit 8 is usually composed of a plurality of ceramic filtration tubes 8a arranged horizontally at substantially equal intervals. The number of the ceramic filtration tubes 8a constituting each filtration unit 8 is not particularly limited as long as it is a plurality, for example, it can be 2 to 50, or 3 to 40, or 4 to 30, or 5 to 20. The cross-sectional shape of the ceramic filtration tube 8a is usually substantially circular, but it can also be substantially elliptical or substantially rectangular, or a combination thereof. The plurality of ceramic filtration tubes 8a constituting each filtration unit 8 are usually arranged horizontally and at substantially equal intervals, but at least a part of them can also have adjacent ceramic filtration tubes in direct contact. In the case where the ceramic filtration tubes 8a arranged horizontally and at substantially equal intervals in the filtration unit 8 form multiple rows, it is preferred that these multiple rows are also arranged at substantially equal intervals.

[0046] As Figures 3 to 5As shown, the rotor 9 generally includes at least a motor 9a, a rotating rod 9b, and a front-end member 9c. The rotor 9 is disposed adjacent to the filtration unit 8 (adjacent to each filtration unit 8 when there are multiple filtration units 8). As shown in the figure, the rotor 9 is generally disposed above the vicinity of the center of the hearth 5 so that the stirring effect extends throughout the filtration chamber 2, but it is not limited thereto. When there is one filtration unit 8, the rotor 9 may also be disposed above a position away from the vicinity of the center of the hearth 5 (for example, at a position approximately midway between the vicinity of the center of the hearth 5 and the inner wall surface 6). When there are two or more filtration units 8, the rotor 9 is preferably disposed at approximately equal distances from each filtration unit. The number of rotors 9 provided is generally one, but multiple rotors may also be provided. When multiple rotors 9 are provided, each rotor is preferably adjacent to the filtration unit 8, and each rotor is preferably disposed at approximately equal distances from the filtration unit (the adjacent filtration unit when there are multiple ones). In addition, when multiple rotors 9 are provided, the hearth 5 is designed such that, when observed in the horizontal direction, except for the position where the discharge flow path is provided, it is at the lowest level (lowest height) directly below at least one of the multiple rotors.

[0047] The motor 9a of the rotor 9 is a component that drives the rotation of the rotating rod 9b and the front-end member 9c at a variable speed. For the motor 9a of the rotor 9, a speed reduction mechanism may be provided together, and in addition, a heater for heating the molten metal and a fan may also be provided. The rotating rod 9b of the rotor 9 is not particularly limited. From the viewpoint of stirring efficiency, its rotation axis is preferably in a substantially vertical direction (that is, the direction in which the filtration chamber 2 of the molten metal filtration device 1 disposed on the horizontal plane is vertically cut longitudinally). The front-end member 9c of the rotor 9 preferably has a gas injection function for promoting the convection / stirring of the molten metal. When the front-end member 9c of the rotor 9 has a gas injection function, the rotating rod 9b may be in the form of a hollow shaft and is configured to supply the gas for injection through this hollow shaft. In this case, a plurality of gas injection ports may be formed on the front-end member 9c. The gas for injection is not particularly limited, and inert gases such as nitrogen and argon are preferred.

[0048] In addition, in order to promote the convection / stirring of the molten metal, the front-end member 9c of the rotor 9 may instead of or in addition to the gas injection mechanism have the shape of a blade / impeller. In addition, in order to promote the convection / stirring of the molten metal, the front-end member 9c of the rotor 9 may be configured to move up and down freely together with the rotating rod 9b instead of or in addition to the gas injection mechanism and / or the blade / impeller shape. In this case, a vertical movement mechanism for the rotating rod 9b and the front-end member 9c may also be further provided together near the motor 9a of the rotor 9.

[0049] The molten metal entering from the liquid inlet 3 is preferably maintained at a certain temperature by the heater 7 disposed in the filtration chamber or further heated to a high temperature. In addition, while being convected / stirred by the rotor 9, it is filtered by the filtration unit 8 composed of a plurality of ceramic filter tubes 8a. When filtering with the filtration unit 8, preferably, the liquid level of the molten metal reaches a level at which the entire filtration unit 8 (or all of them in the case where a plurality of filtration units 8 are provided) is immersed in the molten metal (in Figure 3 , Figure 4 , the imaginary line M represents the liquid level of the molten metal). The filtered molten metal is discharged from the liquid outlet 4. In Figure 5 , two liquid outlets 4 are illustrated, but it is not limited to two. It can also be one, or more than three. Similar to the liquid inlet 3, the opening area of the liquid outlet 4 is appropriately designed according to the desired filtration throughput of the molten metal filtration device 1. The liquid outlet 4 is not particularly limited and may include a rising portion as illustrated in Figure 4 .

[0050] In Figures 3 to 5 , the hearth 5 is composed of a flat portion 5a near the center, a rising portion 5b, and a discharge flow path 5c. The shape of the hearth 5 needs to be designed such that when observed in the horizontal direction, it has the lowest height directly below the rotor 9 except at the location where the discharge flow path 5c is provided, and there are no other particular limitations. In addition, in the case where a plurality of rotors 9 are provided, the hearth 5 is designed such that when observed in the horizontal direction, except at the location where the discharge flow path is provided, it is at the lowest position (lowest height) directly below at least one of the plurality of rotors.

[0051] In one embodiment, from the perspective of stirring efficiency, the area of the flat portion 5a can be 2% or more and 40% or less of the horizontal area of the entire hearth, preferably 3% or more and 30% or less, and more preferably 5% or more and 20% or less. In addition, from the perspective of stirring efficiency, the area of the flat portion 5a can be 80% or more and 300% or less of the horizontal rotation area of the front-end component 9c of the rotor 9, preferably 100% or more and 200% or less.

[0052] The discharge flow path 5c is a flow path for discharging the residual liquid of the molten metal (the discharge liquid of the molten metal containing inclusions or sedimented substances, or the molten metal discharged during device maintenance) by its own weight. Functionally, as in Figure 3As illustrated, the discharge flow path 5c needs to form a descending portion substantially throughout from the hearth to the discharge port. Therefore, when the hearth 5 is designed such that the lowest height is at a position substantially directly below the rotor 9 when viewed horizontally, the height of the installation portion of the discharge flow path 5c is excluded from the considerations of this design. The shape of the discharge flow path 5c can be designed arbitrarily, but by making the downstream flow path width wider than the upstream, the discharge of the residual liquid can be facilitated (refer to Figure 5 ).

[0053] With such a design of the hearth 5, the contact portion between the hearth 5 and the inner wall surface 6 substantially exists at a position higher than the lowest position substantially directly below the rotor 9. Therefore, during the liquid supply / filtration of the molten metal, at either the portion near the liquid supply port 3 on the hearth 5 of the filtration chamber 2 or the opposite side thereof, compared with the position substantially directly below the rotor 9, the molten liquid level on the hearth will be relatively lower (the depth from the molten liquid surface to the hearth is smaller), and a stable and uniform convection of the molten metal without local stagnation will be generated. Furthermore, the degassing performance of gas inclusions such as hydrogen and the performance of preventing pore blockage by cleaning the outer surface of the ceramic filter tube are further improved. Through such a design, further, at different positions on the hearth of the filtration chamber, the performance of preventing pore blockage of the ceramic filter tube is homogenized, and furthermore, the difference in the service life of the filtration performance of the ceramic filter tube becomes smaller, which contributes to the improvement of production efficiency and the reduction of the overall cost of the production line.

[0054] The angle α of the straight line connecting the lowest position substantially directly below the rotor 9 on the hearth 5 (the center point in the case of having the flat portion 5a) to any contact portion between the hearth 5 and the inner wall surface 6 with respect to the horizontal plane is not particularly limited. However, from the balance between the viewpoints of obtaining the above-mentioned desired effects and preventing uneven impurities caused by excessive height difference of the hearth, it can generally be 2 degrees or more to 30 degrees or less, preferably 3 degrees or more to 25 degrees or less, 4 degrees or more to 20 degrees or less, or 5 degrees or more to 15 degrees or less.

[0055] As Figures 3 to 5 shown, from the viewpoint of stirring efficiency, the hearth 5 preferably has a flat portion 5a at a position substantially directly below the rotor 9 (near the center in this figure). It is not necessary to provide such a flat portion at the position substantially directly below the rotor 9 of the hearth 5, and this position can also form a part of the ascending portion. In addition, in Figures 3 to 4In [the figure], the rising portion 5b of the hearth 5 is illustrated as a cross-section of a rising straight line having a certain gradient (rising angle), but it is not necessary to form a continuous rise (such as a rising gradient or a rising step) in all parts in a specified direction from a position substantially directly below the rotor 9 of the hearth 5 to the contact portion of the hearth 5 with the inner wall surface 6. The rising portion 5b of the hearth 5 only needs to rise in at least a part, preferably more than half, of the vertical cross-section in the specified direction, and may have a flat portion (a portion substantially in a horizontal plane) at the non-rising part (a single part or multiple parts). The rising portion 5b of the hearth 5 may also include a stepped portion (constituted by a combination of one or more substantially vertical stepped portions and a substantially horizontal portion, i.e., a step) in at least a part.

[0056] In Figure 6 (a) to (f) of [the figure], several non-limiting embodiments of the cross-section of the rising portion formed on the hearth of the filtration chamber of the molten metal filtration device of the present utility model are illustrated.

[0057] In the figure, with respect to the hearth of the filtration chamber, in the vertical cross-section in the specified direction, from the lowest position to the contact portion of the hearth with the inner wall surface, in addition to a rising straight line having a certain gradient (rising angle) and a rising step having a certain step difference, it may also include a concave curve-shaped rising gradient cross-section such as S1 and / or a convex curve-shaped rising gradient cross-section such as S2.

[0058] In addition, with respect to the hearth of the filtration chamber, in the vertical cross-section in the specified direction, from the lowest position to the contact portion of the hearth with the inner wall surface, instead of a rising straight line having a certain gradient (rising angle), a rising step having a certain step difference, a cross-sectional shape such as S1 and / or S2, or on this basis, it may include a rising gradient such as S3 having a flat portion (substantially horizontal portion) interposed in a part and / or a rising gradient such as S4 having a stepped portion (a combination of a substantially vertical stepped portion and a substantially horizontal portion) interposed in a part.

[0059] In addition, with respect to the hearth of the filtration chamber, in the vertical cross-section in the specified direction, from the lowest position to the contact portion of the hearth with the inner wall surface, instead of a rising straight line having a certain gradient (rising angle), a rising step having a certain step difference, at least one of S1, S2, S3, and S4, or on this basis, it may include a rising gradient such as S5 with a gradually increasing gradient (i.e., the gradient becomes larger in sequence) and / or a stepped rising portion such as S6 with a gradually increasing step difference (i.e., the step difference becomes larger step by step). Alternatively, the hearth of the filtration chamber may also include a rising gradient with a gradually decreasing gradient (i.e., the gradient becomes smaller step by step) and / or a stepped rising portion such as S6 with a gradually decreasing step difference (i.e., the step difference becomes smaller step by step).

[0060] The hearth of the filtration chamber can also be formed by a combination of two or more different cross-sectional shapes in vertical cross-sections in any number of directions from the lowest position towards the contact portion of the hearth with the inner wall surface. Additionally, the hearth of the filtration chamber can be formed with substantially the same cross-sectional shape in any two symmetric directions from the lowest position towards the contact portion of the hearth with the inner wall surface.

[0061] By allowing such a varied cross-sectional shape of the hearth, the design freedom of the hearth is significantly increased, and it is easy to adapt to various variable design factors such as the filtration throughput of the molten metal, the heating temperature, and the structure of the rotor, thereby maximizing the filtration efficiency and further homogenizing the service life of the filtration performance of the ceramic filter tube.

[0062] Description of Reference Numerals

[0063] F: Filtration chamber

[0064] T: Ceramic filter tube

[0065] I: Inlet for molten metal

[0066] U: Filtration unit

[0067] N: Injection nozzle

[0068] W: Inner wall surface of the filtration chamber

[0069] B: Bottom surface / hearth of the filtration chamber

[0070] L: Imaginary line of the molten metal level of the molten metal

[0071] (The above symbols F to L are related to the illustration of the prior art Figure 1 .)

[0072] 1: Molten metal filtration device

[0073] 2: Filtration chamber

[0074] 3: Inlet

[0075] 4: Outlet

[0076] 5: Hearth (bottom surface of the filtration chamber)

[0077] 5a: Planar portion near the center of the hearth (substantially directly below the rotor)

[0078] 5b: Rising portion of the hearth

[0079] 5c: Discharge flow path formed in the hearth

[0080] 6: Inner wall surface

[0081] 7: Heater

[0082] 8: Filtration unit

[0083] 8a: Ceramic filter tube

[0084] 8b: Wedge member

[0085] 9: Rotor

[0086] 9a: Motor

[0087] 9b: Rotating rod

[0088] 9c: Front-end member

[0089] 10: Pedestal

[0090] 11: Housing of the filtration chamber

[0091] S1: Concave curve-shaped rising gradient section formed on the hearth

[0092] S2: Convex curve-shaped rising gradient section formed on the hearth

[0093] S3: Rising gradient section formed on the hearth with a flat part sandwiched therein

[0094] S4: Rising gradient section formed on the hearth with a stepped part sandwiched therein

[0095] S5: Rising gradient section formed on the hearth with a gradually increasing gradient

[0096] S6: Stepped rising part section formed on the hearth with a gradually increasing step difference.

Claims

1. A metal melt filtration device, characterized in that, Comprising: (i) A filtration chamber having an inlet and an outlet for the molten metal, and including a hearths and an inner wall surface; (ii) A filtration unit composed of a plurality of ceramic filter tubes disposed above the hearth in the interior of the filtration chamber for filtering impurities from the molten metal; And (iii) A rotor disposed adjacent to the filtration unit, and in the case where there are a plurality of the filtration units, the rotor is disposed adjacent to each of the plurality of filtration units, and the rotor stirs the molten metal by rotating in a substantially horizontal direction; Except for the portion where the discharge passage is provided, the hearth is at the lowest position directly below the rotor when viewed in the horizontal direction, whereby substantially the entire contact portion between the hearth and the inner wall surface is at a position higher than the lowest position directly below the rotor.

2. The molten metal filtration device according to claim 1, wherein The hearth includes a rising gradient with respect to the horizontal direction and / or a stepped rising portion from the lowest position to at least a part of the contact portion between the hearth and the inner wall surface.

3. The molten metal filtration device according to claim 2, wherein The rising gradient of the hearth with respect to the horizontal direction has different gradients at different positions of the hearth, and / or the stepped rising portion of the hearth has different step differences at different positions of the hearth.

4. The molten metal filtration device according to claim 3, wherein The gradient of the rising gradient of the hearth with respect to the horizontal direction includes a portion that gradually increases from the lowest position to at least a part of the contact portion between the hearth and the inner wall surface, and / or the step difference of the stepped rising portion of the hearth includes a portion that gradually increases from the lowest position to at least a part of the contact portion between the hearth and the inner wall surface.

5. The molten metal filtration device according to claim 2, wherein The rising gradient of the hearth with respect to the horizontal direction forms a curved surface at at least a part of the hearth.

6. The molten metal filtration device according to claim 1 or 2, wherein The filtration unit is composed of a plurality of ceramic filter tubes arranged in parallel at substantially equal intervals in a substantially horizontal direction, In the case where there are a plurality of the filtration units, the rotor is disposed at a substantially equal distance from each of the plurality of filtration units.

7. The molten metal filtration device according to claim 1 or 2, wherein The rotor has a rotation axis extending in a substantially vertical direction at substantially the center of the filtration chamber, and is provided with a gas injection mechanism for promoting the convection of the molten metal.

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