Molten metal filtration member

Abstract

To increase joining strength between a filter body and a side plate.SOLUTION: A molten metal filtration member 10 includes: cylindrical filter bodies 20; a one-end-side side plate 30 with one-end-side insertion holes 32 into each of which one end 22 of the filter body 20 is inserted; one-end-side bonding layers 38 each of which joins an outer peripheral surface 22a of the one end 22 of the filter body 20 to an inner peripheral surface 32a of the one-end-side insertion hole 32; a the-other-end-side side plate 40 with the-other-end-side insertion holes 42 into each of which the other end 24 of the filter body 20 is inserted; and the-other-end-side bonding layers 48 each of which joins an outer peripheral surface 24a of the other end 24 of the filter body 20 to an inner peripheral surface 42a of the the-other-end-side insertion hole 42. At least one of the inner peripheral surface 32a of the one-end-side insertion hole 32 and the inner peripheral surface 42a of the the-other-end-side insertion hole 42 has multiple recesses with a depth of 50 μm or more, and an average depth of the recesses is between 90 μm and 1000 μm, inclusive.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a molten metal filtering element. [Background technology]

[0002] Conventionally, a molten metal filtration element has been known that includes a plurality of cylindrical filter bodies with bottoms and a pair of side plates. The opposing surfaces of the pair of side plates each have an insertion hole into which an end of the filter body is inserted and held. The ends of the filter body are inserted and joined to each other through the insertion hole. In this molten metal filtration element, molten metal supplied from the outer peripheral surface of the filter body flows into the cylindrical interior while being filtered by the filter body, and inclusions are removed before the molten metal flows out from the open end. It has been proposed that such a molten metal filtration element have a ratio of the distance between adjacent insertion holes to the depth of the insertion holes of 0.33 to 0.67 (see, for example, Patent Document 1). This is believed to improve filtration efficiency while maintaining the strength of the side plates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-210254 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although Patent Document 1 claims that it is possible to increase the filtration efficiency while maintaining the strength of the side plates, the bonding strength between the filter body and the side plates is sometimes insufficient, and it has been desired to further increase the bonding strength between the filter body and the side plates.

[0005] The present invention has been made to solve such problems, and a main object of the present invention is to further increase the bonding strength between the filter body and the side plate. [Means for solving the problem]

[0006] [1] The molten metal filtration member of the present invention is A cylindrical filter body; a one-end side plate having a one-end insertion hole into which one end of the filter body is inserted; a first-end joining layer that joins an outer peripheral surface of one end of the filter body and an inner peripheral surface of the first-end insertion hole; an other-end side plate having an other-end side insertion hole into which the other end of the filter body is inserted; an other-end-side joining layer that joins an outer peripheral surface of the other end of the filter body and an inner peripheral surface of the other-end-side insertion hole; and At least one of the inner peripheral surface of the one end insertion hole and the inner peripheral surface of the other end insertion hole has a plurality of recesses with a depth of 50 μm or more, and the average depth of the recesses is 90 μm or more and 1000 μm or less.

[0007] In this molten metal filtration member, at least one of the inner peripheral surface of the one-end insertion hole and the inner peripheral surface of the other-end insertion hole has a plurality of recesses with a depth of 50 μm or more, with an average depth of 90 μm to 1000 μm. As a result, the bonding layer penetrates into the recesses appropriately, thereby increasing the bonding strength between the filter body and the bonding layer and further increasing the bonding strength between the filter body and the side plate.

[0008] [2] In the molten metal filtration member of the present invention (the molten metal filtration member described in [1] above), it is preferable that the average depth of the recesses on at least one of the inner peripheral surface of the one-end insertion hole and the inner peripheral surface of the other-end insertion hole is 200 μm or more and 1000 μm or less. This can further increase the bonding strength between the filter body and the side plate.

[0009] [3] In the molten metal filtration member of the present invention (the molten metal filtration member described in [1] or [2] above), it is preferable that the average surface roughness Ra of at least one of the inner circumferential surface of the one-end insertion hole and the inner circumferential surface of the other-end insertion hole is 50 μm or more and 600 μm or less. This can further increase the bonding strength between the filter body and the side plate.

[0010] [4] In the molten metal filtration member of the present invention (the molten metal filtration member according to any one of [1] to [3] above), it is preferable that the average width of the recesses on at least one of the inner peripheral surface of the one-end insertion hole and the inner peripheral surface of the other-end insertion hole is 200 μm or more and 500 μm or less. This can further increase the bonding strength between the filter body and the side plate.

[0011] [5] In the molten metal filtration member of the present invention (the molten metal filtration member according to any one of [1] to [4] above), the number of the recesses present on a straight line 15 mm long on at least one of the inner peripheral surface of the one-end insertion hole and the inner peripheral surface of the other-end insertion hole is preferably 4 to 30. This can further increase the bonding strength between the filter body and the side plate.

[0012] [6] The molten metal filtration element of the present invention (the molten metal filtration element described in any one of [1] to [5]) may have a maximum load of 1.5 kN or more applied to push out the filter body in at least one of the one end insertion hole and the other end insertion hole. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a perspective view of the molten metal filtration member 10. [Figure 2] FIG. 2 is a cross-sectional view of the molten metal filtration member 10. [Figure 3] 1 is an explanatory diagram of an example of use of the molten metal filtration member 10. FIG. [Figure 4] FIG. 10 is an explanatory diagram of an example of measuring the inner circumferential surface of an insertion hole. [Figure 5] FIG. 10 is an explanatory diagram of an example of measurement of push-out strength. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view of a molten metal filtration element 10. Fig. 2 is a cross-sectional view of the molten metal filtration element 10 (a cross-sectional view cut along a plane including the central axis of the filter body 20).

[0015] The molten metal filtration element 10 includes a filter body 20, a first-end side plate 30 having a first-end insertion hole 32 into which one end 22 of the filter body 20 is inserted, and a second-end side plate 40 having a second-end insertion hole 42 into which the second end 24 of the filter body 20 is inserted. Here, the molten metal filtration element 10 includes 14 filter bodies 20, which are spaced apart from one another in a staggered arrangement. The outer peripheral surface 22a of the first end 22 of the filter body 20 and the inner peripheral surface 32a of the first-end insertion hole 32 are joined by a first-end bonding layer 38. The outer peripheral surface 24a of the second end 24 of the filter body 20 and the inner peripheral surface 42a of the second-end insertion hole 42 are joined by a second-end bonding layer 48. A first-end gasket 39 is disposed between the end surface 22b of the first end 22 of the filter body 20 and the bottom surface 32b of the first-end insertion hole 32. An other-end packing 49 is disposed between the end surface 24 b of the other end 24 of the filter body 20 and the bottom surface 42 b of the other-end insertion hole 42 .

[0016] The filter body 20 is a porous cylindrical member made of a ceramic material, such as alumina or silicon carbide. The filter body 20 may be made of, for example, alumina aggregate bound with an inorganic binder such as aluminum borate (9Al2O3·2B2O3). The inorganic binder may be, for example, needle-shaped crystals with an aspect ratio of 2 to 50. The filter body 20 has a cylindrical shape with a hole 20h coaxial with the filter body 20, an open end 22, and a closed end 24. A portion of the outer peripheral surface 24a of the other end 24 forms a tapered surface 24c whose diameter decreases toward the end surface 24b. The filter body 20 has, for example, a length of approximately 870 mm, an outer diameter of approximately 100 mm, and an inner diameter of approximately 60 mm. The dimensions of the filter body 20 may be adjusted appropriately depending on the number of filter bodies 20.

[0017] The one-end side plate 30 is a dense plate-shaped member made of a ceramic material, such as silicon carbide. Note that "dense" refers to a material dense enough to prevent molten metal from passing through (the same applies hereinafter). The ceramic material may be, for example, SiO-bonded SiC (also referred to as SiO-SiC) or SiN-bonded SiC (also referred to as SiN-SiC). A one-end insertion hole 32 is provided in one main surface 31 of the one-end side plate 30. The one-end insertion hole 32 is a circular recess opening in the main surface 31, and its inner diameter is larger than the outer diameter of the filter body 20. A through-hole 32h is provided in the bottom surface 32b of the one-end insertion hole 32, coaxial with the one-end insertion hole 32, and penetrates to the other main surface of the one-end side plate 30. The through-hole 32h is formed to have approximately the same diameter as the hole 20h in the filter body 20. The one-end side plate 30 has a thickness of, for example, approximately 50 mm, and the one-end insertion hole 32 has a depth of approximately 28 mm. The inner peripheral surface 32a of the one-end insertion hole 32 may expand in diameter from the bottom surface 32b toward the opening. In this case, the inclination of the inner peripheral surface 32a with respect to the axis of the one-end insertion hole 32 may be approximately 2.0°. The one-end side plate 30 can be produced, for example, by mixing raw material powder (aggregate), an organic binder, and water to prepare a clay, molding this clay into the shape of the one-end side plate 30, and firing it. The particle size distribution of the aggregate may be such that the particle size exceeding 2000 μm is 1.0% to 15.0%, the particle size exceeding 500 μm to 2000 μm is 30.0% to 60.0%, the particle size exceeding 90 μm to 500 μm is 10.0% to 30.0%, and the particle size 90 μm or less is 20.0% to 35.0%. The particle size distribution of the aggregate is preferably such that the particle size exceeding 500 μm is 50.0% or more, more preferably 60.0% or more, and even more preferably 65.0% or more. The particle size distribution is measured by mass using a vibrating sieve in accordance with JIS Z 8815-1994. The aggregate is preferably SiC. The clay preferably contains 80.0% or more by mass of SiC. The SiC content of the clay may be 98.0% or less by mass. The clay preferably has a moisture content of 2.0% by mass or more and 5.0% by mass or less. Clay or a sintering aid may be added to the clay. The inner peripheral surface 32a and bottom surface 32b of the one-end insertion hole 32 may be machined or may be left as a fired surface.

[0018] The inner peripheral surface 32a of the one-end insertion hole 32 has a plurality of recesses each having a depth of 50 μm or more. The average depth (also referred to as the average depth) of these recesses (recesses having a depth of 50 μm or more, the same applies hereinafter) is 90 μm or more and 1000 μm or less. The average depth is preferably 100 μm or more, more preferably 200 μm or more, and may be 300 μm or more. The average width (also referred to as the average width) of these recesses may be 200 μm or more, 300 μm or more, or 400 μm or more. The average width may be 700 μm or less, 600 μm or less, or 500 μm or less. The number of these recesses present on a straight line having a length of 15 mm may be 4 or more, 5 or more, or 8 or more. The number of recesses on a 15 mm straight line may be 30 or less, 20 or less, or 15 or less. The average value of the arithmetic surface roughness Ra (also referred to as the average surface roughness Ra) of the inner circumferential surface 32a of the one-end insertion hole 32 may be 50 μm or more, 100 μm or more, or 150 μm or more. The average surface roughness Ra may be 1000 μm or less, 800 μm or less, or 600 μm or less. The arithmetic mean roughness Ra is a value measured in accordance with JIS B0601-2001. The average depth, average width, and number of recesses, as well as the average surface roughness Ra of the inner circumferential surface 32a, may be determined by measuring a 15 mm long, arbitrary straight line in the insertion direction of the filter body 20 (the left-right direction in FIG. 2) on a representative portion of the inner circumferential surface 32a, or may be the average value of measurements on multiple straight lines (e.g., three straight lines). The average depth, average width, and number of the recesses and the average roughness of the inner peripheral surface 32a can be adjusted as appropriate, for example, by adjusting the particle size distribution of the raw material powder used when producing the one-end side plate 30 or the moisture content of the clay.

[0019] The one-end bonding layer 38 is disposed between the outer peripheral surface 22a of the one end 22 of the filter body 20 and the inner peripheral surface 32a of the one-end insertion hole 32, bonding them together. The one-end bonding layer 38 tightly adheres the outer peripheral surface 22a of the one end 22 of the filter body 20 to the inner peripheral surface 32a of the one-end insertion hole 32 to a degree that prevents molten metal from penetrating between them. The one-end bonding layer 38 may be formed, for example, from mortar. The mortar is preferably an alumina mortar, more preferably one containing 75% or more by mass of alumina. The alumina content of the mortar may be 95% or less by mass. Alumina mortar can suppress contamination of molten metal, such as molten aluminum. The mortar may contain a glass component such as SiO2, which makes it soft when hot, when filtering molten metal, but hard when cold before or after use. The mortar may be hardened by natural drying and / or heat drying at a temperature of not more than 100° C. The thickness of the one end side bonding layer 38 is, for example, about 1.5 mm.

[0020] The one-end packing 39 is disposed between the end surface 22b of the one end 22 of the filter body and the bottom surface 32b of the one-end insertion hole 32. It mainly absorbs longitudinal dimensional changes of the filter body 20 due to thermal expansion and contraction, and maintains close contact between the filter body 20 and the one-end side plate 30. The one-end packing 39 is formed in an annular shape with approximately the same diameter as the bottom surface 32b of the one-end insertion hole 32, and has a hole 39h connecting the hole 20h of the filter body 20 and the through-hole 32h of the one-end insertion hole 32. The one-end packing 39 may be formed of ceramic fiber such as alumina fiber. The thickness of the one-end packing 39 is, for example, approximately 12 mm.

[0021] The other-end side plate 40 is a dense plate-like member made of a ceramic material, such as silicon carbide. The ceramic material may be, for example, SiO-bonded SiC (also referred to as SiO-SiC) or SiN-bonded SiC (also referred to as SiN-SiC). A other-end insertion hole 42 is provided in one main surface 41 of the other-end side plate 40. The other-end insertion hole 42 is a circular recess that opens into the main surface 41, and its inner diameter is larger than the outer diameter of the filter body 20. A bottom surface 42b of the other-end insertion hole 42 does not have a through-hole. The other-end side plate 40 has a thickness of, for example, approximately 45 mm, and the other-end insertion hole 42 has a depth of approximately 28 mm. The inner peripheral surface 42a of the other-end insertion hole 42 may expand in diameter from the bottom surface 42b toward the opening. In this case, the inclination of the inner peripheral surface 42a with respect to the axis of the other-end insertion hole 42 may be approximately 4.0°. The other-end side plate 40 can be produced, for example, by mixing raw material powder (aggregate), an organic binder, and water to prepare a puddle, molding this puddle into the shape of the other-end side plate 40, and firing it. The particle size distribution and material of the aggregate, the proportion of SiC in the puddle, and the moisture content can be the same as those described for the one-end side plate 30. Clay or a sintering aid may be added to the puddle. The inner peripheral surface 42a and bottom surface 42b of the other-end insertion hole 42 may be machined surfaces, or may be fired surfaces.

[0022] The inner circumferential surface 42a of the other-end insertion hole 42 has a plurality of recesses each having a depth of 50 μm or more. The average depth (also referred to as the average depth) of these recesses (recesses having a depth of 50 μm or more, the same applies hereinafter) is 90 μm or more and 1000 μm or less. The average depth is preferably 100 μm or more, more preferably 200 μm or more, and may be 300 μm or more. The average width (also referred to as the average width) of these recesses may be 200 μm or more, 300 μm or more, or 400 μm or more. The average width may be 700 μm or less, 600 μm or less, or 500 μm or less. The number of these recesses present on a straight line having a length of 15 mm may be 4 or more, 5 or more, or 8 or more. The number of recesses on a 15 mm straight line may be 30 or less, 20 or less, or 15 or less. The average value of the arithmetic surface roughness Ra (also referred to as the average surface roughness Ra) of the inner circumferential surface 42a of the other-end insertion hole 42 may be 50 μm or more, 100 μm or more, or 150 μm or more. The average surface roughness Ra may be 1000 μm or less, 800 μm or less, or 600 μm or less. The arithmetic mean roughness Ra is a value measured in accordance with JIS B0601-2001. The average depth, average width, and number of recesses, as well as the average surface roughness Ra of the inner circumferential surface 42a, may be determined by measuring a 15 mm long, arbitrary straight line in the insertion direction of the filter body 20 (the left-right direction in FIG. 2) on a representative portion of the inner circumferential surface 42a, or may be the average value of measurements on multiple straight lines (e.g., three straight lines). The average depth, average width, and number of the recesses and the average roughness of the inner peripheral surface 42a can be adjusted as appropriate, for example, by adjusting the particle size distribution of the raw material powder used when producing the other end side plate 40 or the moisture content of the clay.

[0023] The other-end bonding layer 48 is disposed between the outer peripheral surface 24a of the other end 24 of the filter body 20 and the inner peripheral surface 42a of the other-end insertion hole 42, bonding them together. The other-end bonding layer 48 tightly adheres the outer peripheral surface 24a of the other end 24 of the filter body 20 to the inner peripheral surface 42a of the other-end insertion hole 42 to such an extent that molten metal does not enter between them. The other-end bonding layer 48 may be formed of, for example, mortar. The mortar may be the same as the mortar described for the one-end bonding layer 38. The thickness of the other-end bonding layer 48 is, for example, about 1.5 mm.

[0024] The other-end packing 49 is disposed between the end surface 24b of the other end 24 of the filter body 20 and the bottom surface 42b of the other-end insertion hole 42, and mainly absorbs longitudinal dimensional changes due to thermal expansion and contraction of the filter body 20, thereby maintaining close contact between the filter body 20 and the other-end side plate 40. The other-end packing 49 is formed in a circular shape with approximately the same diameter as the bottom surface 42b of the other-end insertion hole 42. The other-end packing 49 may be formed of ceramic fiber such as alumina fiber, for example. The thickness of the other-end packing 49 is, for example, approximately 12 mm.

[0025] A manufacturing example of the molten metal filtration member 10 will be described. First, the other-end side plate 40 is prepared, and the material for the other-end gasket 49 is placed on the bottom surface 42b of the other-end insertion hole 42. Then, the material for the other-end bonding layer 48 (mortar) is applied to the inner circumferential surface 42a of the other-end insertion hole 42 and the outer circumferential surface 24a of the other end 24 of the filter body 20, and the other end 24 of the filter body 20 is inserted into the other-end insertion hole 42 to a predetermined depth. Next, the one-end side plate 30 is prepared, and the material for the one-end gasket 39 is placed on the bottom surface 32b of the one-end insertion hole 32. Then, the material for the one-end bonding layer 38 (mortar) is applied to the inner circumferential surface 32a of the one-end insertion hole 32 and the outer circumferential surface 22a of the one end 22 of the filter body 20, and the one end 22 of the filter body 20 is inserted into the one-end insertion hole 32 to a predetermined depth. Thereafter, natural drying and / or heat drying is carried out at a temperature of, for example, 100° C. or less, whereby the filter body 20 is joined to the one end side plate 30 and the other end side plate 40, and the molten metal filtration member 10 is obtained.

[0026] An example of use of the molten metal filtration element 10 will be described with reference to Figure 3. Figure 3 is an explanatory diagram of an example of use of the molten metal filtration element 10. The molten metal filtration element 10 is fixed in a filtration chamber 52 of a storage tank 50. The storage tank 50 is a container lined with a refractory material such as firebricks, and is separated into a filtration chamber 52 and a discharge chamber 56 by a partition wall 54. An inlet 51 is provided at the top of the side wall of the filtration chamber 52, an opening 53 is provided in the partition wall 54, and an outlet 57 is provided in the side wall of the discharge chamber 56 at a position lower than the inlet 51. The molten metal filtration element 10 is arranged in the filtration chamber 52 of the storage tank 50 so that the other end side panel 40 faces the inlet 51 and the one end side panel 30 faces the partition wall 54. When a wedge 59 is driven between the other-end side plate 40 and the side wall of the filtration chamber 52, the one-end side plate 30 abuts against the partition wall 54, fixing the molten metal filtration element 10 within the filtration chamber 52. In this state, when molten metal such as aluminum metal or aluminum alloy is supplied through the inlet 51 of the storage tank 50, the molten metal flows from the outer surface of the filter body 20 through the pores of the filter body 20 to the holes 20h, filtering out solid impurities such as oxides. The molten metal from which the solid impurities have been removed then flows through the opening 53 in the partition wall 54, accumulates in the discharge chamber 56, and is then discharged through the outlet 57 for use in the production of metal foil, metal plate, metal parts, and the like. The filtration performance of the molten metal filtration element 10 deteriorates with use. However, since the molten metal filtration element 10 is configured as a replaceable cartridge by inserting and removing the wedge 59, the storage tank 50 can be continuously used simply by replacing the molten metal filtration element 10. Here, if the bond strength between the filter body 20 and the one-end side plate 30 or the other-end side plate 40 is weak, the bond between them may come loose when the molten metal filtration element 10 is transported or when it is set in or removed from the storage tank 50. Furthermore, if the bond between them comes loose before the molten metal filtration element 10 is set in the storage tank 50, there is a risk that the molten metal cannot be stably filtered. However, in the molten metal filtration element 10 of the present invention, the bond strength between the filter body 20 and the one-end side plate 30 or the other-end side plate 40 is strong, allowing for stable filtration. In this way, the present invention can provide a highly reliable molten metal filtration element 10.

[0027] The molten metal filtration member 10 described above has a plurality of recesses with a depth of 50 μm or more on the inner circumferential surface 32a of the one-end insertion hole 32 and the inner circumferential surface 42a of the other-end insertion hole 42, with the average depth being 90 μm to 1000 μm. Therefore, the one-end bonding layer 38 and the other-end bonding layer 48 appropriately penetrate into the recesses, thereby increasing the bonding strength between the filter body 20 and the one-end bonding layer 38 or the other-end bonding layer 48, and further increasing the bonding strength between the filter body 20 and the one-end side plate 30 or the other-end side plate 40. This allows for a highly reliable molten metal filtration member 10 to be provided. Note that an average depth of the recesses of 1000 μm or less is desirable because it is less likely that the recesses will cause damage to the side plates.

[0028] In this molten metal filtration member 10, the one-end punching strength, which is the maximum load required to push the filter body 20 out of the one-end insertion hole 32, may be 1.5 kN or more. This one-end punching strength is preferably 2 kN or more, more preferably 3 kN or more, and even more preferably 4 kN or more. In addition, in this molten metal filtration member 10, the other-end punching strength, which is the maximum load required to push the filter body 20 out of the other-end insertion hole 42, may be 1.5 kN or more. This other-end punching strength is preferably 2 kN or more, more preferably 3 kN or more, and even more preferably 4 kN or more.

[0029] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0030] For example, in the above-described embodiment, both the inner circumferential surface 32a of the one-end insertion hole 32 and the inner circumferential surface 42a of the other-end insertion hole 42 have a plurality of depressions with a depth of 50 μm or more, with an average depth of 90 μm to 1000 μm, but this is not limited to this. For example, if stress is particularly concentrated between the inner circumferential surface 32a of the one-end insertion hole 32 and the one-end bonding layer 38 due to differences in the shape or arrangement of each component, only the inner circumferential surface 32a may satisfy this requirement. Also, if stress is particularly concentrated between the inner circumferential surface 42a of the other-end insertion hole 42 and the one-end bonding layer 48, only the inner circumferential surface 42a may satisfy this requirement.

[0031] In the above-described embodiment, the other end 24 of the filter body 20 is closed, but it may be open. Furthermore, although no through-hole is provided in the bottom surface 42b of the other-end insertion hole 42, a through-hole may be provided. Furthermore, although part of the outer peripheral surface 24a of the other end 24 is tapered surface 24c, it is not necessary for this to be the tapered surface 24c. [Example]

[0032] Hereinafter, examples in which the bonding strength between the filter body and the side plate of the molten metal filtration member of the present invention was examined will be described as examples. Experimental Examples 2 to 11 correspond to examples of the present invention, and Experimental Example 1 corresponds to a comparative example of the present invention.

[0033] [Experimental Example 1] (Making the side panels) The side panels were fabricated as follows. First, the raw powder (aggregate) used consisted of 0% SiC with a particle size exceeding 2000 μm, 35% SiC with a particle size exceeding 500 μm and 2000 μm, 30% SiC with a particle size exceeding 90 μm and 500 μm, and 35% SiC with a particle size of 90 μm or less. This powder was mixed with carboxymethyl cellulose (CMC) as an organic binder and water to obtain a clay with a moisture content of 5.5 mass%. The clay contained clay and a sintering aid. This clay was molded and fired in an air atmosphere at 1430°C for 3 hours to obtain the side panels. The side panels were 50 mm thick, with insertion holes 104 mm in diameter and 28 mm in depth. A 56 mm diameter through-hole was drilled at the bottom of the insertion hole. Then, a packing made of alumina fiber and having a thickness of approximately 12 mm was placed at the bottom of the insertion hole.

[0034] (Joining of side plate and filter body) A porous filter body was prepared, consisting of alumina aggregate bound together by needle-shaped aluminum borate crystals. This filter body had a length of approximately 870 mm, an outer diameter of 100 mm, an inner diameter of 60 mm, one open end and the other closed end, and a bottom thickness of 20 mm. This filter body was machined to a length of approximately 200 mm, leaving the bottom. Mortar containing 85% Al2O3 and 2% SiO2 by mass was then applied to the outer peripheral surface of the open side of the filter body and the inner peripheral surface of the insertion hole in the side plate, and the open side of the filter body was inserted into the insertion hole in the side plate. The filter body was then air-dried for 12 hours and then heated and dried at 80°C for another 12 hours to bond the side plate and filter body. Only one filter body was used.

[0035] (Measurement of the inner surface of the insertion hole) The side panel was split, and the inner circumferential surface of the insertion hole was extracted as a test specimen. Surface measurements were performed on three representative locations of this test specimen along a 15 mm straight line. A Keyence VR-3000 one-shot 3D measuring microscope was used to measure the arithmetic surface roughness Ra, the number of dents (per 15 mm), the dent width (μm), and the dent depth (μm), and the average values were calculated. Only dents with a depth of 50 μm or greater were measured for the number, width, and depth. Figure 4 shows an example of a measurement of the inner circumferential surface of the insertion hole. Figure 4A is an explanatory diagram showing the observation direction. Figure 4B is a photograph of the test specimen. Figure 4C is a contour diagram showing the height of the test specimen. Figure 4D is an example of a measured roughness curve.

[0036] (Measurement of punching strength) An explanatory diagram of a measurement example of the push-out strength is shown in Figure 5. As shown in Figure 5, a test jig was inserted through the through-hole in the side plate and pressed to apply a load to the bottom surface of the filter body. Then, the load when the filter body was pushed out of the side plate was measured as the push-out strength (kN).

[0037] [Experimental Examples 2-11] The side panels were produced in the same manner as in Experimental Example 1, except that the particle size distribution of the aggregate (SiC) in the raw material powder and the moisture content of the clay were as shown in Table 1.

[0038] [Experimental Results] Table 1 summarizes the measurement results of the inner peripheral surface of the insertion hole and the punching strength. As shown in Table 1, in Experimental Examples 2 to 11, in which the inner peripheral surface of the insertion hole had multiple depressions with a depth of 50 μm or more and an average depth of 90 μm to 1000 μm, the punching strength was 1.5 kN, indicating that the bonding strength between the filter body and the side plate could be further increased. Note that, although the bonding strength of the open end side of the filter body was evaluated here, it is presumed that similar results would be obtained for the bonding strength of the closed end side of the filter body.

[0039] [Table 1] [Industrial Applicability]

[0040] The present invention can be used in the field of manufacturing metal products. [Explanation of symbols]

[0041] 10 Molten metal filtration element, 20 filter body, 20h hole, 22 one end, 22a outer peripheral surface, 22b end face, 24 other end, 24a outer peripheral surface, 24b end face, 30 one end side plate, 32 one end insertion hole, 32a inner peripheral surface, 32b bottom surface, 32h through hole, 38 one end bonding layer, 39 one end packing, 40 other end side plate, 42 other end insertion hole, 42a inner peripheral surface, 42b bottom surface, 48 other end bonding layer, 49 other end packing, 50 storage tank, 51 inlet, 52 filtration chamber, 53 opening, 54 partition wall, 56 molten metal discharge chamber, 57 outlet, 59 wedge.

Claims

1. A cylindrical filter body; a one-end side plate having a one-end insertion hole into which one end of the filter body is inserted; a first-end joining layer that joins an outer peripheral surface of one end of the filter body and an inner peripheral surface of the first-end insertion hole; an other-end side plate having an other-end side insertion hole into which the other end of the filter body is inserted; an other-end-side joining layer that joins an outer peripheral surface of the other end of the filter body and an inner peripheral surface of the other-end-side insertion hole; and At least one of the inner peripheral surface of the one end side insertion hole and the inner peripheral surface of the other end side insertion hole has a plurality of recesses having a depth of 50 μm or more, and the average depth of the recesses is 90 μm or more and 1000 μm or less. Molten metal filtering material.

2. an average depth of the recess in at least one of the inner peripheral surface of the one end side insertion hole and the inner peripheral surface of the other end side insertion hole is 200 μm or more and 1000 μm or less; The molten metal filtration element according to claim 1 .

3. an average surface roughness Ra of 50 μm or more and 600 μm or less on at least one of the inner circumferential surface of the one end side insertion hole and the inner circumferential surface of the other end side insertion hole; The molten metal filtration element according to claim 1 .

4. an average width of the recess in at least one of the inner circumferential surface of the one end side insertion hole and the inner circumferential surface of the other end side insertion hole is 200 μm or more and 500 μm or less; The molten metal filtration member according to any one of claims 1 to 3.

5. the number of the recesses present on a straight line having a length of 15 mm on at least one of the inner peripheral surface of the one-end side insertion hole and the inner peripheral surface of the other-end side insertion hole is 4 or more and 30 or less; The molten metal filtration member according to any one of claims 1 to 3.

6. a maximum load applied to push out the filter body through at least one of the one end side insertion hole and the other end side insertion hole is 1.5 kN or more; The molten metal filtration member according to any one of claims 1 to 3.

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