Molten metal filtration unit

Abstract

The present invention addresses the problem of providing a molten metal filtration unit that is more easily placed in a prescribed position in a filtration chamber compared with a conventional molten metal filtration unit. This problem is solved by means of a molten metal filtration unit comprising a pair of side plates and a substantially cylindrical filtration tube connected substantially perpendicularly to each of the pair of side plates, wherein: the pair of side plates comprise a first side plate that comprises a through-hole at a site connected to the filtration tube, and a second side plate that is closed at a site connected to the filtration tube; each side plate comprises at least one leg part suspended from the bottom surface of the side plate; and when the longitudinal direction of the filtration tube is substantially horizontal, the lowest point of the leg part of the second side plate in the vertical direction is lower than the lowest point of the leg part of the first side plate in the vertical direction.

Description

Molten metal filtration unit

[0001] The present invention relates to a molten metal filtration unit to be installed in a molten metal filtration apparatus that filters molten metal such as aluminum. More specifically, the present invention relates to a molten metal filtration unit that facilitates installation of the filtration chamber at a predetermined position when the molten metal filtration unit is installed in the filtration chamber of the molten metal filtration apparatus.

[0002] Molten metals such as aluminum used in the production of castings typically contain impurities such as hydrogen and non-metallic inclusions, such as oxides. For example, dissolved hydrogen in the molten metal can form cavities called porosity in the casting, and oxides and other substances can become inclusions in the casting. These cavities and inclusions are undesirable because they can be the starting point for fracture in the casting. Therefore, filtration devices have been developed to filter the molten metal and remove impurities such as inclusions contained in the molten metal.

[0003] To achieve this goal, a molten metal filtering device is typically used in which a molten metal filtering unit having a plurality of ceramic filter tubes for filtering impurities from the molten metal is placed in a filtering chamber provided with an inlet and an outlet (see Patent Document 1). In such a molten metal filtering device, the molten metal filtering unit needs to be taken in and out of the filtering chamber before and after use. Therefore, the molten metal unit needs to be moved to a predetermined position in the filtering chamber before use.

[0004] As a means for moving the molten metal unit to a predetermined position in the filtering chamber, a method of pressing the molten metal filtering unit with a hydraulic jack or a pantograph jack or the like is employed.

[0005] JP 2014-210254 A

[0006] However, due to its weight, it was difficult to accurately move the molten metal filtration unit to a predetermined position by means such as pressing. Furthermore, in filtration of molten metal, the molten metal filtration unit needs to be in close contact with the outlet side of the filtration chamber, but due to the weight of the molten metal filtration unit, fine adjustment of the position was difficult. Furthermore, in a molten metal filtration device that has been used repeatedly, fine adjustment of the position of the molten metal filtration unit is even more difficult due to friction with the molten metal filtration unit and the influence of distortion of the molten metal filtration device itself caused by repeated expansion and contraction due to the heat of the molten metal.

[0007] Therefore, the problem to be solved by the present invention is to provide a molten metal filtration unit that eliminates the above-mentioned disadvantages, i.e., that is easier to arrange at a predetermined position within a filtration chamber compared to conventional molten metal filtration units. Note that throughout this specification, the "molten metal filtration unit" may also be referred to simply as the "filtration unit." Also, throughout this specification, the "molten metal filtration device" may also be referred to simply as the "filtration device."

[0008] After extensive research, the inventors discovered that the above-mentioned problems could be solved by improving the legs provided on the bottom surfaces of the side plates constituting the filtration unit. Specifically, the inventors discovered that by making the lengths of the legs of each side plate different, the operability of moving the filtration unit to a desired position within the filtration chamber and fine-tuning its placement could be improved due to the weight of the filtration unit itself, i.e., due to an imbalance in the weight balance of the filtration unit, and thus completed the present invention. Note that in the above description and this specification, the term "first side plate" refers to a side plate having a through-hole at the location connected to the filtration tube, and the term "second side plate" refers to a side plate whose location connected to the filtration tube is closed. In this specification, the term "imbalance in weight balance" of a filtration unit refers to an imbalance in the weight balance of the overall structure or a partial structure when compared to a filtration unit described below as a typical example.

[0009] A typical aspect of the present invention is as follows: A molten metal filtering unit comprising a pair of side plates and a substantially cylindrical filter tube connected substantially perpendicularly to each of the pair of side plates, wherein the pair of side plates comprises a first side plate having a through hole at a location connected to the filter tube and a second side plate the location connected to the filter tube is closed, each side plate has at least one leg hanging down from a bottom surface of the side plate, and when the longitudinal direction of the filter tube is substantially horizontal, the lowest vertical position of the leg of the second side plate is lower than the lowest vertical position of the leg of the first side plate.

[0010] According to the filtration unit of the present invention, when the longitudinal direction of the filtration tube is approximately horizontal, the lowest vertical position of the legs of the second side plate is lower than the lowest vertical position of the legs of the first side plate, and this makes it easier to move the filtration unit to the desired position and fine-tune its position within the filtration chamber of the filtration device due to the imbalance in weight, thereby providing an excellent advantage that could not be foreseen from conventional filtration units, namely, being able to contribute to improving the efficiency of the entire installation process of the filtration device.

[0011] Fig. 1 shows a typical example of a filtration unit and a filtration device, Fig. 2 shows a schematic view of a filtration unit according to an embodiment of the present invention, and Fig. 3 shows a schematic view of a first side plate of a filtration unit according to an embodiment of the present invention.

[0012] The filtration unit of the present invention is disposed in a filtration chamber of a filtration device. To facilitate understanding of the features of the filtration unit of the present invention, a typical example of the filtration unit and filtration device will first be described with reference to FIG.

[0013] 1 shows a filtration device 101, which includes an inlet 102, a filtration chamber 103, a tapping chamber 105, and tapping outlets 106 and 110. The filtration unit 104 includes a first side plate 107, a second side plate 108, and a substantially cylindrical filtration tube 109 connected substantially perpendicularly to the side plates. Although not shown in FIG. 1, the first side plate 107 has a through-hole at the location connected to the filtration tube 109, and the second side plate 108 has a closed location connected to the filtration tube 109.

[0014] Furthermore, although FIG. 1 is a schematic diagram of the entire filtration device observed from a direction in which the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the filtration unit will be described in this specification as if the filtration unit and the filtration device were observed from the same direction, unless otherwise specified.

[0015] In molten metal filtering, a filtration unit 104 is disposed in a filtration chamber 103, and molten metal, such as aluminum or an aluminum alloy, is supplied to the inlet 102. The molten metal supplied from the inlet 102 passes through a filtration tube 109 provided in the filtration unit 104 disposed in the filtration chamber 103, thereby removing impurities such as oxides contained in the molten metal. The filtered molten metal flows from the filtration tube 109 through a through-hole provided in the first side plate 107, into the tapping chamber 105 from the tapping outlet 110, and then passes through the tapping chamber 105 before being discharged from the tapping outlet 106. The discharged molten metal is sent to a molten metal storage device, a metal processing device (neither of which are shown) that processes the molten metal, or the like.

[0016] In general, the filtering device 101 filters SiC aggregate into Si ３ N ４ The size of the filtration device 101 is not particularly limited as long as the filtration unit 104 can be placed in the filtration chamber 103.

[0017] The filtration unit of the present invention is a filtration unit in which each side plate has at least one leg hanging down from the bottom surface of the side plate, and when the longitudinal direction of the filtration tube is approximately horizontal, the lowest vertical position of the leg of the second side plate is lower than the lowest vertical position of the leg of the first side plate.

[0018] In such a filtration unit, for example, when the longitudinal direction of the filtration tube is approximately horizontal, the vertical length of the legs provided on the second leg section is greater than the vertical length of the legs provided on the first side plate. Hereinafter, unless otherwise specified, the vertical length of the legs provided on each side plate will also be simply referred to as the "leg length."

[0019] The above-described configuration of the filtration unit of the present invention, when placed in the filtration chamber of a filtration device, makes it easy to move the filtration unit to a desired position and fine-tune its placement due to the imbalance in the weight balance of the filtration unit. More specifically, when the filtration unit of the present invention is placed in a substantially horizontal filtration chamber, the filtration unit is pressed against the outlet-side wall surface (i.e., the first side plate side). As a result, the first side plate and the outlet-side wall surface can be easily brought into close contact with each other.

[0020] As the filtration chamber repeatedly filters molten metal, it expands and contracts due to the heat of the high-temperature molten metal. Furthermore, the footings (also called "bases") of the hearth that contact the filtration unit wear out as the filtration unit is repeatedly installed. As a result, the hearth becomes less horizontal due to aging, making it difficult to install the filtration unit in the filtration chamber. However, the filtration unit of the present invention applies pressure to the tap-side wall surface even when installed in a deteriorated filtration chamber, making it easy to tightly seal the first side plate and the tap-side wall surface.

[0021] In one aspect of the present invention, when the longitudinal direction of the filtration tube is approximately horizontal, the ratio of the vertical length of the leg portion of the first side plate to the vertical length of the leg portion of the second side plate may be 0.20 or more and less than 1.0, preferably 0.4 or more and 0.8 or less, and more preferably 0.5 or more and 0.7 or less.

[0022] When the length ratio is 0.20 or more, the weight balance of the filtration unit is not excessively unbalanced, and accidents caused by the filtration unit tipping over when not in use can be prevented. Furthermore, when the length ratio is less than 1.0, the length of the legs of the first side plate is shorter than the length of the legs of the second side plate, and therefore, when the filtration unit is placed in the filtration chamber, the weight balance of the filtration unit is not unbalanced, and it is therefore easy to move the filtration unit to a desired position and fine-tune its placement.

[0023] The filtration unit of the present invention has a characteristic leg portion as described above, but the method for forming the leg portion is not particularly limited. For example, when the leg portion is formed together with the side plates using a metal mold or a casting mold, the metal mold or casting mold may be adjusted to obtain the desired leg length. Furthermore, after forming the filtration unit, the leg portion of the first side plate may be polished or the like so that the length of the leg portion of the first side plate is shorter than the length of the leg portion of the second side plate.

[0024] In one aspect of the present invention, the ratio of the total ground contact area of ​​all legs of the molten metal filtration unit to the total bottom area of ​​the pair of side plates may be 0.015 to 0.075, preferably 0.020 to 0.060, more preferably 0.025 to 0.050.

[0025] When the area ratio is 0.015 or more, the filtration unit can be placed more stably on the legs. When the area ratio is 0.075 or less, the contact area between the filtration unit and the hearth due to the legs is reduced, thereby preventing the filtration unit from adhering to the hearth.

[0026] The contact area of ​​the legs may be calculated from the dimensions of the bottom surfaces of the legs. Alternatively, the contact area of ​​the legs may be measured by applying ink to the legs and measuring ink marks, or by placing the filtration unit on pressure-sensitive paper and measuring marks left behind. The bottom area of ​​the side panels can be calculated from the dimensions of the bottom surfaces of the side panels.

[0027] As described above, in the filtration unit of the present invention, each side plate has at least one leg extending downward from the bottom surface of the side plate. The shape, position, and number of the leg on the side plate are not particularly limited.

[0028] In one aspect of the present invention, the filtration unit may have at least two legs on the first side plate and one leg on the second side plate. By providing the legs in this manner, even if the filtration unit is placed in a filtration chamber that has deteriorated over time, the filtration unit can be supported at at least three points, allowing the filtration unit to be stably placed.

[0029] In this aspect, the filtration unit may preferably have at least two legs near both longitudinal ends of the bottom surface of the first side plate and one leg at approximately the longitudinal center of the bottom surface of the second side plate. By providing the legs in this manner, the filtration unit can be positioned more stably.

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiment shown in the drawings.

[0031] FIG. 2 shows a filtration unit according to one embodiment of the present invention. However, because FIG. 2 is for illustrative purposes, the dimensional ratios and the number of filtration tubes may differ from the actual figures. The filtration unit 104 of the present invention includes a leg 201 on the bottom surface of the first side plate 107 and a leg 202 on the bottom surface of the second side plate 108. FIG. 2 illustrates a filtration unit in which the longitudinal direction of the filtration tubes is substantially horizontal. In this case, the vertical length H1 of the leg 201 is different from the vertical length H2 of the leg 202, and the length H2 of the leg 202 is greater than the length H1 of the leg 201. Therefore, the lowest position of the leg 202 is lower than the lowest position of the leg 201. Note that, in FIG. 2, the legs 201 and 202 are shown slanted toward the first side plate (the left side of FIG. 2), but the shape of the legs is not particularly limited.

[0032] Therefore, when the filtration unit of the present invention is placed on a substantially horizontal hearth, it tilts toward the first side plate 107. As a result, a pressing force is applied to the tap port side wall surface so that the filtration unit tilts, making it easier to come into close contact with the tap port side wall surface. The filtration unit of the present invention may also be provided with a ceramic fiber packing 203 on the first side plate 107. The pressure applied to the tap port side wall surface causes the packing 203 to come into close contact with the wall surface, preventing leakage of the molten metal.

[0033] FIG. 3 shows the filtration unit 104 as viewed from the first side plate 107. The filtration unit of the present invention can be easily moved to a desired position and finely adjusted for placement, allowing it to be tightly attached to the wall surface of the outlet port. That is, when the filtration unit 104 is placed in the filtration chamber, it can be positioned so that pressure is applied evenly to the four corners of the packing 203 (points a, b, c, and d in FIG. 3 ), thereby preventing leakage of molten metal. Whether pressure is being applied evenly to the packing 203 can be determined by measuring the thickness of the packing after compression at four points a, b, c, and d of the packing 203 when the filtration unit 104 is placed in the filtration chamber. The stronger the pressure, the greater the packing shrinkage. Therefore, if pressure is being applied evenly to the packing 203, the thickness of the packing after compression at the four points a, b, c, and d will be approximately the same. In the present invention, it can be determined whether the pressure applied to the packing is uniform or not from the difference between the point where the thickness of the packing after compression is maximum and the point where the thickness is minimum among the four points a, b, c, and d.

[0034] Although the molten metal filtration unit according to the present invention has been described above using specific embodiments, it is not intended to be limited to these embodiments. In particular, it should be noted that the molten metal filtration unit according to the present invention can be applied to any molten metal filtration unit as long as it is characterized by legs hanging from the bottom of at least one pair of side plates. For example, the filtration unit according to the present invention is not limited by the shape, length, number, etc. of the filtration tubes. The filtration unit according to the present invention is not limited to the filtration units illustrated in the specific embodiments described above. The scope of the subject matter that can be encompassed by the present invention should be determined by the appended claims.

[0035] <Additional Embodiments Regarding the Structure of the Filter Tube> The structure of the filter tube included in the molten metal filtering unit according to the present invention is not particularly limited except as defined in the appended claims. The filter tube may satisfy specific relationships regarding the inventive shape or dimensions as exemplified in the following items [1] or [2].

[0036] [1] Additional embodiment 1 of filter tubes of molten metal filtration unit An additional example of a molten metal filtration unit includes a filter tube specified as follows: A molten metal filtration unit including: a plurality of cylindrical ceramic filter tubes arranged substantially parallel to each other, each having a substantially circular cross section perpendicular to the longitudinal direction on its outer surface and inner surface, and a pair of side plates disposed at both longitudinal ends of the plurality of ceramic filter tubes, the plurality of ceramic filter tubes having a first end on the side from which the molten metal is discharged and a second end on the other side, and at least some of the plurality of ceramic filter tubes having a longitudinal length L of a portion of the outer surface of the filter tube exposed to the molten metal １ The outer diameter of the filtration tube is D １ The longitudinal length of the part of the inner surface of the filtration tube exposed to the molten metal is L ２ The inner diameter of the filtration tube is D ２ Then, the following two relations are satisfied: (1) L １ / D １ ≧8.5 (2) L ２ / D ２ A molten metal filtration unit that satisfies all of the following requirements:

[0037] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is larger than the inner diameter at the second end. (ii) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is 100.5% or more and 120% or less of the inner diameter at the second end. (iii) In at least some of the plurality of ceramic filter tubes, the opening shape of the first end encompasses the opening shape of the filter tube-side end of a substantially circular through-hole provided in the side plate on the discharge side of the pair of side plates when viewed in the longitudinal direction. (iv) In the above (iii), the inner diameter of the through-hole in the side plate on the discharge side is smaller than the inner diameter of the filter tube-side end. (v) In the above (iv), the inner diameter of the end of the through hole in the side plate on the melt discharge side is 80% to 99.5% of the inner diameter of the end of the filter tube installation side. (vi) At least some of the plurality of ceramic filter tubes are fitted and fixed at each longitudinal end in a recess formed in the side plate via a packing having a shape that fits the recess. (vii) At least some of the plurality of ceramic filter tubes are formed of a porous material having a porosity of 25% to 50%.

[0038] [2] Additional embodiment 2 of filter tubes of molten metal filtration unit An additional example of a molten metal filtration unit includes a filter tube specified as follows: A molten metal filtration unit including a plurality of cylindrical ceramic filter tubes arranged substantially parallel to each other, each having a substantially circular cross section perpendicular to the longitudinal direction on its outer surface and inner surface, and a pair of side plates arranged at both longitudinal ends of the plurality of ceramic filter tubes, wherein the plurality of ceramic filter tubes have a first end on the side from which the molten metal is discharged and a second end on the other side, and at least some of the plurality of ceramic filter tubes have a longitudinal length L of a portion of the outer surface of the filter tube exposed to the molten metal. １The outer diameter of the filtration tube is D １ The longitudinal length of the part of the inner surface of the filtration tube exposed to the molten metal is L ２ The inner diameter of the filtration tube is D ２ Then, the following two relations are satisfied: (1) L １ / D １ ≧8.5 (2) L ２ / D ２ A molten metal filtration unit that satisfies all of the above requirements.

[0039] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) In at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is larger than the inner diameter at the second end. (ii) In (i) above, in at least some of the plurality of ceramic filter tubes, the inner diameter at the first end is 100.5% or more and 150% or less of the inner diameter at the second end. (iii) In at least some of the plurality of ceramic filter tubes, the opening shape of the first end encompasses the opening shape of the filter tube-side end of a substantially circular through-hole provided in the side plate on the discharge side of the pair of side plates when viewed in the longitudinal direction. (iv) In (iii) above, in the through-hole in the side plate on the discharge side, the inner diameter at the discharge side end is smaller than the inner diameter at the filter tube-side end. (v) In the above (iv), the inner diameter of the end of the through hole in the side plate on the melt discharge side is 70% to 99.5% of the inner diameter of the end of the filter tube installation side. (vi) At least some of the plurality of ceramic filter tubes are fitted and fixed at each longitudinal end in a recess formed in the side plate via a packing having a shape that fits the recess. (vii) At least some of the plurality of ceramic filter tubes are formed of a porous material having a porosity of 25% to 50%.

[0040] <Additional Embodiments Related to the Structure of the Side Plates> The structure of the pair of side plates included in the molten metal filtration unit according to the present invention is not particularly limited except as defined in the appended claims. These two side plates may have substantially the same external shape, being approximately rectangular parallelepiped plates, and may also satisfy specific relationships related to the inventive shapes or dimensions, as exemplified in the following items [1] or [2].

[0041] [1] Additional embodiment 1 of side plates of molten metal filtration unit An additional example of a molten metal filtration unit includes a pair of side plates specified as follows: A molten metal filtration unit including a pair of side plates and a substantially cylindrical filtration tube connected substantially perpendicularly to the pair of side plates, wherein the pair of side plates include: a first side plate having a through hole at a location connected to the filtration tube, and a second side plate the location connected to the filtration tube is closed, and when the longitudinal direction of the filtration tube is substantially horizontal and the first side plate is located to the left of the filtration tube and the second side plate is located to the right of the filtration tube, at least one of the pair of side plates has a bottom formed so that either the left side bottom edge or the right side bottom edge is positioned vertically higher than the other bottom edge.

[0042] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) When the longitudinal direction of the filter tube is approximately horizontal and the first side plate is located on the left side of the filter tube and the second side plate is located on the right side of the filter tube, the first side plate has a bottom portion formed so that either the left side or the right side bottom edge is positioned vertically higher than the other bottom edge, when the first side plate has a bottom portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge, the second side plate has a bottom portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge, or when the first side plate has a bottom portion formed so that the right side bottom edge is positioned vertically higher than the left side bottom edge, the second side plate has a bottom portion formed so that the right side bottom edge is positioned vertically higher than the left side bottom edge. (ii) When the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, at least one of the pair of side plates has a step portion formed so that either the left side bottom edge or the right side bottom edge is positioned vertically higher than the other bottom edge. (iii) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the pair of side plates have a step portion formed so that the left side bottom edge is positioned vertically higher than the right side bottom edge. (iv) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the step portion consists of a first bottom portion which is the lowest part, and a second bottom portion which is formed to be located vertically higher than the first bottom portion, and the ratio (W1 / W2) of the horizontal length W1 of the first bottom portion to the horizontal length W2 of the second bottom portion is 0.1 or more and 6.0 or less, where W1 and W2 are lengths in a direction parallel to the longitudinal direction of the filtration tube.(v) In (ii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the step portion comprises a first bottom portion which is the lowest part, and a second bottom portion which is formed to be located vertically higher than the first bottom portion, and the ratio (W1 / H) of the horizontal length W1 of the first bottom portion to the vertical length H from the first bottom portion to the second bottom portion is 0.1 or more and 11 or less, where W1 is the length in a direction parallel to the longitudinal direction of the filtration tube. (vi) When the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, at least one of the pair of side plates is formed so that either the left side bottom edge or the right side bottom edge is located vertically higher than the other bottom edge, and is provided with a bottom edge having a first bottom edge that is the lowest part and a sloped portion that connects the first bottom edge to the bottom edge that is located vertically higher. (vii) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal, and the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the ratio (W1' / W2') of the horizontal length W1' of the first bottom edge to the horizontal length W2' of the sloped portion is equal to or greater than 0 and equal to or less than 6.0, where W1' and W2' are lengths parallel to the longitudinal direction of the filtration tube. (viii) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the ratio (W1' / H') of the horizontal length W1' of the first bottom to the vertical length H' from the end of the inclined portion that contacts the first bottom to the other end of the inclined portion is not less than 0 and not more than 320, where W1' is the length in a direction parallel to the longitudinal direction of the filtration tube. (ix) In (viii) above, when the longitudinal direction of the filtration tube is approximately horizontal, the first side plate is located on the left side of the filtration tube, and the second side plate is located on the right side of the filtration tube, the angle θ1 between the inclined portion and the vertical direction is not less than 60° and not more than 89°.(x) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal and the first side plate is located on the left side of the filtration tube and the second side plate is located on the right side of the filtration tube, the pair of side plates are formed so that the left bottom edge is located higher in the vertical direction than the right bottom edge, and are provided with a first bottom edge that is the lowest portion and a bottom edge that has a slope connecting the first bottom edge to the left bottom edge. (xi) In (vi) above, when the longitudinal direction of the filtration tube is approximately horizontal and the first side plate is located on the left side of the filtration tube and the second side plate is located on the right side of the filtration tube, the pair of side plates are formed so that the right bottom edge is located higher in the vertical direction than the left bottom edge, and are provided with a first bottom edge that is the lowest portion and a bottom edge that has a slope connecting the first bottom edge to the right bottom edge. (xii) A molten metal filtering device having an outlet for molten metal, wherein the molten metal filtering unit described in (ix) above has an inclined portion formed so that when the longitudinal direction of the filter tube is approximately horizontal and the first side plate is located on the left side of the filter tube and the second side plate is located on the right side of the filter tube, the right side base is positioned vertically higher than the left side base, and the first side plate is arranged so that the first side plate is in contact with the outlet, and the filtering device has a wedge-shaped protrusion on the hearth, the protrusion having an angle θ2 between a surface in contact with the molten metal filtering unit and a horizontal plane, and the sum of θ1 and θ2 satisfies 61° or more and 114° or less.

[0043] [2] Additional embodiment 2 of side plates of molten metal filtration unit An additional example of a molten metal filtration unit includes a pair of side plates specified as follows: A molten metal filtration unit including a pair of side plates and a substantially cylindrical filtration tube connected substantially perpendicularly to each of the pair of side plates, wherein the pair of side plates includes: a first side plate having a through hole at a location connected to the filtration tube, and a second side plate the location connected to the filtration tube is closed, each side plate has a leg extending downward from a bottom surface of the side plate, and the number of legs provided on the first side plate is at least one more than the number of legs provided on the second side plate.

[0044] The molten metal filtration unit according to this additional embodiment may further include the following non-limiting configurations: (i) the first side plate includes two legs and the second side plate includes one leg; (ii) two legs are provided near both longitudinal ends of the bottom surface of the first side plate and one leg is provided approximately in the longitudinal center of the bottom surface of the second side plate; (iii) when the molten metal filtration unit is placed on a horizontal surface and observed vertically from above, the area of ​​the molten metal filtration unit is expressed as the product of the length of the molten metal filtration unit in the longitudinal direction of the filtration tube and the longitudinal length of the side plate, S1' is the area of ​​the molten metal filtration unit, S2' is the total area of ​​the contact areas of all the legs of the molten metal filtration unit, and the area ratio S2' / S1' is 0.0020 or more and 0.015 or less.

[0045] The embodiments of the present invention will be specifically described with reference to the following examples, but the present invention is not limited to these examples.

[0046] The filtration units of Examples 1 to 6 and Comparative Example were prepared with the dimensions shown in Table 1. The bottom surface of the side plates of the filtration unit had a long side of 720 mm and a short side of 60 mm (therefore, the total bottom area of ​​the pair of side plates was 86,400 mm). ２ In the table, the leg heights H1 and H2 are as shown in Figure 2. "Leg height H1" refers to the vertical length of the leg provided on the bottom surface of the first side plate, and "Leg height H2" refers to the vertical length of the leg provided on the bottom surface of the second side plate. The filtration device has a filtration chamber with a volume of 1.39 m ３ The hearth of the filtering chamber of the filtering device is provided with a base for the filtering unit, and when the filtering unit is placed, the filtering tube is set to be approximately horizontal. ３ N ４ The refractory material used was a refractory material bonded with SiO2.

[0047] Molten metal filtering operation using a filtering unit The following steps (a) to (e) were performed as one filtering operation using the filtering units of Examples 1 to 6 and the Comparative Example. (a) Installation of the filtering unit The filtering unit was placed in the filtering chamber so that its legs rested on the base inside the filtering chamber. A pressing jack was used to press the filtering unit so that the first side plate of the filtering unit was in close contact with the wall surface on the tap side. The filtering unit was fixed by driving a wedge between the second side plate and the wall surface of the filtering device. (b) Preheating of the filtering device The filtering device was heated at 80°C / hour using a temperature-controlled heater installed in the filtering chamber. After the controlled temperature of the temperature-controlled heater reached 800°C, heating using the temperature-controlled heater was continued to maintain the controlled temperature at 800°C. Heating using the temperature-controlled heater continued for 150 hours. (c) Filtration of molten metal 1,000 t of molten metal at 680°C to 750°C was charged into the filtration device and filtered over a period of 14 days. (d) Cooling of filtration device The filtration device was left to cool until the filtration unit reached room temperature. (e) Removal of filtration unit The wedge between the second side plate and the wall of the filtration device was removed, and the filtration unit was removed from the filtration device.

[0048] Evaluation of ease of placement of filtration unit Six workers fixed the filtration unit in the filtration chamber so that the first side plate of the filtration unit was in close contact with the wall surface of the outlet side of the filtration chamber, as in step (a) of the above filtration work. After fixing the filtration unit, the thickness of the packing was measured at four points a, b, c, and d of the packing in Figure 3. The difference between the maximum and minimum values ​​of the measured thicknesses was recorded, and the average value of the six workers was calculated. The average value was evaluated as follows: A: 1.0 mm or less B: More than 1.0 mm and 1.5 mm or less C: More than 1.5 mm and 2.0 mm or less D: More than 2.0 mm

[0049] The ease of placement of the filtration unit was evaluated by the same six workers after the filtration unit was installed in the filtration chamber for the first time (i.e., after step (a) of the first filtration operation) and after the 15th molten metal filtration operation (i.e., after step (a) of the 16th filtration operation).

[0050] The dimensions of the filtration unit and the evaluation results are shown in Table 1.

[0051] The filtration unit of the present invention can be easily moved to a predetermined position within the filtration chamber using legs provided at the bottom of the side plates that make up the filtration unit. Therefore, the filtration unit of the present invention can easily prepare for filtration of molten metal and improves the efficiency of filtering impurities from molten metal such as aluminum, and can be used in various industries that require such filtering, such as the metal industry and the steel industry.

[0052] 101: Filtration device 102: Inlet port 103: Filtration chamber 104: Filtration unit 105: Outlet chamber 106, 110: Outlet port 107: First side plate 108: Second side plate 109: Filtration tube 201: Leg of first side plate 202: Leg of second side plate 203: Gasket

Claims

1. A molten metal filtration unit comprising a pair of side plates and a substantially cylindrical filtration tube connected to each of the pair of side plates substantially perpendicularly, wherein the pair of side plates includes a first side plate having a through hole at a location connected to the filtration tube, and a second side plate having a location connected to the filtration tube blocked, each side plate includes at least one leg vertically provided from the bottom surface of the side plate, and when the longitudinal direction of the filtration tube is substantially horizontal, the lowest position in the vertical direction of the leg of the second side plate is lower than the lowest position in the vertical direction of the leg of the first side plate, the molten metal filtration unit.

2. The molten metal filtration unit according to claim 1, wherein when the longitudinal direction of the filtration tube is substantially horizontal, the ratio of the length in the vertical direction of the leg of the first side plate to the length in the vertical direction of the leg of the second side plate is 0.20 or more and less than 1.

0.

3. The molten metal filtration unit according to claim 1, wherein the total ground contact area of all the legs in the molten metal filtration unit is 0.015 or more and 0.075 or less with respect to the total bottom area of the pair of side plates.

4. The molten metal filtration unit according to claim 3, wherein the total ground contact area of all the legs in the molten metal filtration unit is 0.020 or more and 0.060 or less with respect to the total bottom area of the pair of side plates.

5. The molten metal filtration unit according to claim 1, comprising at least two legs on the first side plate and one leg on the second side plate.

6. The molten metal filtration unit according to claim 5, comprising at least two legs near both longitudinal ends of the bottom surface of the first side plate and one leg at a substantially central portion in the longitudinal direction of the bottom surface of the second side plate.

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